Since we have support for ACC loading, the errors thrown by `paint` are no longer
sufficiently informative. Even before that it was already hard to correlate source 
and locus of painting errors.

Example
```
$> python3 main.C51A.py
Traceback (most recent call last):
  File "main.C51A.py", line 33, in <module>
    cell = A.cable_cell(morph, labels, decor)
RuntimeError: cable_cell: cable (cable 6 0 1) overpaints
```
This adds more details to the error message
```
$> python3 main.C51A.py
Traceback (most recent call last):
  File "main.C51A.py", line 33, in <module>
    cell = A.cable_cell(morph, labels, decor)
RuntimeError: cable_cell: Setting property 'ion-reversal-potential' on region '(region "soma_group")' overpaints at '(cable 6 0 1)'
```

* Make brunel.py setup faster.
* Use one generator for both populations.

filter out death test on daint single_node_release

Exports all symbols so arbor can be compiled as set of shared libraries. 

In order to export all symbols correctly, one macro per library and one global macro are added. The content of the macros is determined at configure time depending on build variant (static/shared), compiler, and platforms (linux, mac os) and goes into the library's include directory as `export.hpp` when installed (at build time it resides at cmake's temporary build directory). The per-library macro is named `ARB_LIBNAME_API` and goes in front of to-be-exported symbols. The global macro is `ARB_SYMBOL_VISIBLE`. 

This PR adds the annotation in all of the places where it is required. Most of them are in the public headers (and corresponding sources) but some are also added in internal headers, which were required for the unit tests to link properly.

Fixes #1752

Half-half dev and user docs on NMODL optimisation. Actually apply that advice in hh.mod

PyArbor I/O routines now try to cast `filename` arguments to a string.
This allows passing `pathlib.Path` objects.

Example
```py
here = Path(__file__).parent
cat = A.load_catalogue(here / 'local-catalogue.so')
```

* Some badges corrected (build) and added (Gitter)
* Minor Spack backports
* Small updates to `release.rst`

Closes #1822. Adds a separate tutorial for extracellular signal predictions using LFPykit to the docs. Adds some minor improvements to the corresponding python example file. Introduces Intersphinx for linking to other documentation.

* Users may not give dt < 0 to simulation.run()
* Add and throw domain_error.

* Update VERSION to `v0.6.1-dev`
* Updates to `doc/release.rst`
* Update Zenodo citation info for v0.6
* Update copyright info and maintainers in `spack/package.py` from upstream
* Fix error in build-badge docs

* bump version to v0.6-rc
* Update `MANIFEST.in` and `scripts/run_python_examples.sh`
* Update Release instructions `docs/contrib/release.rst`
* Fix missing quotes in `python/example/single_cell_nml.py`
* Add testing to sdist creation in `ciwheel.yml`
* Rename `basic.yml` to `test-everything.yml`
   * Remove Python examples step from matrix (mostly because plotting takes much CPU on macos)
   * change to build /w nml
   * add test of pip builds (`pip install` in addition to CMake builds)
      * Python examples are tested here, once is enough.

# Changes

- `cable_cell_global_properties` now holds a catalogue directy
- fixes for tests, examples, and python bindings accordingly

# Linked Issues
Fixes #1446 

- build-catalogue
  - now installed by pip
  - enable GPU-backends
  - isolate from being installed in a non-default dir
  - rename to arbor-build-catalogue
  - allow hand-written C++ mechanisms to be linked in the same catalogue.
- CMake
  - enable PIC on arbor always to allow linking to shared objects
  - use relative paths when configuring a-b-c, to make relocation less of a problem
- Python
    - ensure a-b-c is installed by pip, along with headers and libarbor.a
    - throw errors if tools (cmake scripts, arbor package, modcc) missing
    - transition setup.py setuptools -> skbuild.
- Wheels
    - Add NML2 support to wheels
    - scripts/build-wheels.sh builds wheels, in principle valid for submission to PyPI, on your own hardware. This should be kept in sync with .github/workflows/ciwheel.yml
    - scripts/patchwheel.py corrects the rpath in the libraries in the wheels, working around a bad interplay between auditwheel and skbuild, see pypa/auditwh...

* Pyarb specific.
* `proc_allocation_shim()` throws error if user sets threads to zero.
* `arbor.context` constructor accepts `threads` set to `"avail_threads"`, which sets the number of threads to `arbenv::thread_concurrency()`
  * This introduces a dependency on arbenv for Pyarb.
* Docs and tests added.

Fixes #1692 

Add a modified version of the benchmark cell example that uses dry run scaling.

- Add support for profiling externally loaded mechanisms.
- Move the profiler calls out of the generated C++ code into the `arb::mechanism` methods. 
- Remove the `--profile` flag from the modcc flags. 
- Replace `_` delimiter with `:` in profiler. 
- Replace `const char*` with `const std::string&` for profiler region representation.
- Profiler may now contain empty regions that were registered but not profiled, so add some code to filer those out when generating final profile.

- Bump CMake to 3.18 for better CUDA support.
- Clean-up our use of said support.
- Remove old cruft and workarounds.
- Maintenance in CI: enable MacOS 11; bump CMake versions to 3.18 / 3.22; bump bors CMake to 3.18

Fixes #1790 

- Implement a new constructor for `domain_decomposition` from a vector of `group_descriptions`. The new constructor performs various checks on the given `group_descriptions` and throws an appropriate exception if any problem is found. It is the only available constructor for `domain_decomposition`.
- Make the various members of `domain_decomposition` private and implement their getters.  
- Expose the `domain_decomposition` constructor to the python interface through a `partition_by_group` function.
- Add unit tests. 
- Add documentation.

Documents the release cycle.

Refactor the CV-cable logic from `fvm_layout.cpp`. Specifically, move `cv_geometry_from_ends` into the new public header `cv_data.hpp` and rename it to `cv_data_from_locset`, and move `pw_over_cable` into another new public header `util/piecewise_over_cable.hpp`. 
Create a new public class `cell_cv_data`, similar to the private `cv_geometry` but which only carries the cv information for a single cable-cell. Add a new constructor to `cv_geometry` which takes `cell_cv_data` as an argument. 
Add new public function `intersect_region` that takes as arguments a cable-cell, a region on that cell and a `cell_cv_data` object and returns a vector of CV indices and proportions belonging to the region. 
Add docs, python wrapper and unit tests. 

Fixes #1720. 

Replace the `partition_load_balance` function assumed that gap-junction connections are always double-sided (i.e. if gid `x` has a gap-junction connection from peer gid `y`, then gid `y` must also have a gap-junction connection from peer gid `x`). This used to be a requirement that was checked prior to #1682. Since then, single-sided gap-junctions are in principle allowed, but `partition_load_balance` still operates under the bidirectional gap-junction connection assumption resulting in some gids being present in multiple cell-groups. 
This PR modifies the `partition_load_balance` function to do the following: 
1. On each rank, generate a gj_connection list per cell. (gj_connection list is a vector of gids that have an outgoing connection ending at the cell under consideration). 
2. On each rank, gather all the gj_connection lists for each cell in the network. 
3. On each rank, modify the global list of gj_connections in the network to make all gj_connections bidirectional. 
4. On each rank, use the global list of gj_connections in the network to partition the graph. 

Fixes #1767.

- make fmt a dependency of libmodcc, not modcc
- set FMT_HEADER_ONLY as a compiler flag to avoid double definition

* Create a script that generates `diff.log` if git submodules have tags more recent that the commit they're currently at.
* A Github Action runs this script monthly.
* _If_ updates found, Github Action creates an Issue like so: https://github.com/brenthuisman/arbor/issues/9
* Actually updating the git submodule and Spack file are still manual

First step in addressing #1731

Check for errors in the solvers before the `finalize` stage and return early if errors were encountered. 

Fixes #1722.