* Sync Cable Cell page names and ordering between sections (concept, python, cpp). Except cpp cable cell page. Is still one big page.
* Move CV definition across categories to consistent location.
* Move decor to separate page (cpp currently missing decor documentation) because it's a top-level concept that should be in the TOC like the other ingredients of the cable cell.
* Slight rework of Concept intro and Cable Cell pages.
* The Cable Cell page is now basically an intro, and lay out how the other pages/concepts relate to each other.

Online STDP is implemented in the synapse and
and demonstrated by recording an STDP curve in
an example.

* fix nmodl comment parsing
* proper handling of \r
* fix segmentation fault when api_state is null
* add unit tests

* add function unit parsing
* add unit tests

Mirror only master branch and tags.

Caused by a typo. The correct version is being used in the non-simd printer.

Reomove Travis CI integration.

* remove Travis yaml and build scripts
* remove Travis badges from README and RTD docs
* replace Travis badge with GitHub Actions badge
* add a RTD badge to the README

Fixes #1338.

* Make Gitlab CI push images to CSCS' JFrog registry reg.giuv.cscs.ch so that sarus can pull images on Daint again. 
  This URL is probably temporary until JFrog officially goes into production later this month.
  Unfortunately JFrog is currently behind the firewall.
* Upgrade g++ to g++8 on the Docker image.
* Only require libxml when compiling with NeuroML support.

* Move contents of `arbornml` to to `arborio` 
* `arborio` will be built with NeuroML2 morphology support if `ARB_CMAKE_NEUROML` is set. 
* Wrap `arborio::neuroml` and `arborio::morphology_data` for pyarb.
* Add documentation.
* add `neuroml` flag to `setup.py`

Fixes #1256
Fixes #1234

Add more GitHub actions CI configurations
* min and max versions of ubuntu, clang and gcc for linux
* MacOS tests with min and max clang versions.

Fixes #1337

Fixes #1340.

* Added a `POST_EVENTS` procedure to nmodl, that takes an argument that represents the time since the last spike on the cell. In the event of multiple detectors on the cell, and multiple spikes on the detectors within the same integration period, all spikes will be processed by the synapse. Spikes are processed only once and then cleared.
* Added 3 vectors to the shared state required to dispatch post-events: `cv_to_cell` map, `time_since_spike` holding max(num_detectors) slots per cell, and `src_to_spike` mapping spike sources (detectors) to slots in `time_since_spike`.
* Renamed `vec_ci_` to `vec_di_` (to better reflect that it stands for **domain index**). Named the new `cv_to_cell` index as `vec_ci_` in the mechanisms.
* Fixed existing unit tests and added new tests for the new post-events functionality.

Fixes #1206

First phase of dynamically loaded mechanism catalogues.

- Add functionality to load and use catalogues from DSOs in Python and C++.
- Add documentation and support scripts to build catalogues DSOs.
- Re-factor CMakeLists.txt for mechanisms
- Limitations
  - Needs (compatible, preferably identical) arbor sources when building catalogues
  - Can only work on MacOS and Linux (uses dlfnc)

Ranges (both <,> and FROM/TO) can now be real-valued and negative.

- Allow negative and real numbers  in `<..., ...>` and `FROM ... TO ...`
- Add and extend tests.

* Respect CMAKE_INSTALL_PREFIX in python lib path

* Set `base` and `platbase` to the CMAKE_INSTALL_PREFIX, if defined,
when asking Python for the default python lib install path.

* Differentiate between explicit and default prefix.

* Test for defaulted CMAKE_INSTALL_PREFIX, in which case, use the system
python site packages path, so that it's overall less excitingly awful in
python virtual environments. If you want /usr/local, set it.

* Used Sphinx glossary directive to create terms that can be referred to in `concepts/morphology.rst` and `concepts/labels.rst`.
* Added note box on difference with Neuron, add source for NEURON cylinder discretisation
* Parameters added to svg generation script: turn off colors, root
* Fix cpp TOC duplication, match ordering in other sections.
* State default cv policy
* center/re -> midpoints
* Clarify and remove compartment term

Introduce two minor changes to the Python API
to handle mechanism_catalogues idiomatically.

Instead of

import arbor as A

cat = A.default_catalogue()

if cat.has('hh'):
  print("Found HH.")

for mech in cat.keys():
   print("*", mech)

we can now write

import arbor as A

cat = A.default_catalogue()

if 'hh' in cat:
  print("Found HH.")

for mech in cat:
   print("*", mech)

which is closer to the expectations of Python users.

* Add docs tutorial page for single_cell_recipe.py example
* Adapted single_cell_recipe.py slightly
* Improved labels and fixed some broken cross-linking
* Fixed a typo here and there

* Set VERSION to 0.5.1-dev

* Add link to Zenodo entry for version 0.5 release.

Numpy is now explicitly required for use in the Python probes interface.

Fix some broken hyperlinks in the rst documentation.

* Add the ability to use json and pybind11 libraries installed on the system instead of the
  vesrsions of those libraries bundled as submodules in the Arbor repository
  * Turned on by default
  * Toggled using the new `ARB_USE_BUNDLED_LIBS` CMake flag
* Update documentation for installation
* Update CI and pip workflows to opt in to the bundled libraries

* Add unit test that checks the expected contribution of an
annulus to the embed_pwlin integrated area, when a zero-length segment
with differing radii exists in the segment tree.