* Delete symlinks from repository for Windows devs
* Dropped extension of executable scripts to follow shell convention
* set executable bits in scripts/

Co-authored-by: Robin De Schepper <robin.deschepper93gmail.com>
Co-authored-by: Brent Huisman <brent@huisman.pl>

* Raise KeyError in catalogue.
* Raise KeyError in label_dict.

The C++ label parse code was returning the error type in the value part of a `parse_hopefully<std::any>`,
and not in the error slot.

The `label_dict` Python wrapper caches label strings and their descriptions in order to
provide a convenient Python iterator interface and `[]` access. These were not being
properly updated or set when the label_dict was constructed from a C++ label_dict.

* Update URLs to arbor-sim.org
* update badge links

Add a CI test for ARM-SVE

- compiles and runs the unit tests with vectorization enabled for the `armv8.2-a+sv` architecture
- uses a dedicated gitlab runner on ault.cscs.ch

Fixes #1498

Fixes issue #1529.

* Adapt CSS for the HTML5 transition in docutils 0.17
* Fix some reST markup errors
* Add meta-tag to enable indexation control at Google (current indexation appears at least a year old).

Fix mistakes reported by @Helveg in the Python tutorial docs. 

* Add a GH workflow to build and run Arbor tests and examples with Clang sanitizers.
* Fix some uninitialized struct members; missing `override` qualifiers.

* Use a struct with meaningful field names instead of a `std::pair` to represent elements in `pw_elements`.
* Describe explicitly the semantics of the zip operation.
* Update implementation and add unit tests to suit.
* Add comment explaining `pw_elements::equal_range`.
* Remove parameter names from unused parameters in `impl::piecewise_pairify`.

* Correct bounds check order in communicator.
* Use `.at()` in test recipe to catch failures in bound checking.

* Exit with correct exit code from Python test runners.
* Fix unit tests that were using older APIs.

* Remove std::filesystem to workaround OSX features; use `std::string` in interfaces expecting a path.

Set option `-mcpu=aarch64` for target `aarch64-apple-darwin`

In response to:

https://gizmodo.com/u-s-federal-investigators-are-reportedly-looking-into-1846707144

Rationale:
* CodeCov didn't detect the breach for two months
* They took a further 2 weeks to alert users after that
* Their efforts to address the issue after that have been painful to watch
  * https://github.com/codecov/codecov-action/issues/281#issuecomment-823407167

* fix mech_vec
* fix fvm_discretize
* small fixes

* Fixes incorrect `current-clamp` generated s-expression. 
* Adds unit test.

Fixes #1486