Bsb-core

* Added a very basic Arbor adapter

* WARNING: Removed the cell cache API, the cell cache is still there internally but
spoofed and not to be used relied on in any user code anymore!
* Running repeated NEST simulations no longer causes strange IO issues, growing
device labels, or module loading warnings and has an example (280, 292, 295).
* Added support for partial (re)connection of networks (303).
* The PlacementSet API can now be used during labelled connectivity by passing the
`labels` kwarg. The labels of the current connection can be accessed inside the
`connect` function as `self.label_pre` and `self.label_post` (310).
* Added `network.merge` function (278).
* Added `get_rank` and `broadcast` to adapter interface so that `mpi4py` can
remain an optional dependency (283).
* More progress reporting during reconstruction (305).
* Fixed NEST spike recorders (284).
* Added NEST fork installation instructions.
* Added support for external sources of placement and connectivity (273).

* BREAKING: NEURON devices will by default target all sections instead of 1
soma section.
* BREAKING: `section_type` changed to `section_types` list for devices.
* BREAKING: All `NeuronDevice` child implementations need to override
`validate_specifics` where each can validate their config.
* BREAKING: Fixed the long standing bug that spikes in NEURON where recorded
as (2xN) instead of (Nx2) datasets.
* BREAKING: `adapter.collect_output` must be passed the `simulation` object.
* Fixed a bug where `spike_devices` with fixed spike times didn't record data.
* NEURON adapter now uses `nrn-patch` v3.0.0
* Added a `voltage_clamp` NEURON device.
* Added support for weight recorders in the NEST adapter (248).
* NEST adapter's `spike_recorder` stores all cell types that occur in a dataset,
is used later on to infer display information when plotting.
* NEURON adapter's `LocationRecorder` now stores section id.
* Network-cache phased out of targetting mechanisms.
* Added `__main__.py` for situations where shell command is unavailable.
* Added `network.get_gid_types` to retrieve the cell types of a vector of GIDs.
* Added `network.assert_continuity` to check all `PlacementSet`s form a single
continuous chain of GIDs starting from 0.
* Fixed a bug where relays without targets would cause errors.
* Fixed NEURON adapter's `time` vector in result files.
* Fixed NEURON adapter's `index_relays` for targetless relays.
* Added stricter validation of config for the `SpikeGenerator` device.
* [cerebellum] Optimized Golgi to granule cell connectivity algorithm.
* [cerebellum] Optimized mossy to glomerulus connectivity algorithm.
* Added `branch.children`.
* Added `cell_type.get_placement_set`.
* Added `get_result_config`.
* Added a `--version` command to the CLI.
* The `time` recorder for NEURON simulations is fixed.
* `*.h5` files and the `build` directory are gitignored.
* Added `range` kwarg to `plot_traces`.
* `plot_traces` will pass all extra kwargs to the `make_subplots` call.
* Added `gaps` kwarg to `hdf5_plot_psth` to control gaps in Bar graph.
* Plot axis labels now display units in square brackets.
* Added an example that shows how to color the branches of a morphology by type.

* Fixed broken on release `by_label` targetting
* `mouse_cerebellum_cortex.json` is now scalable and ID-free.