Release Notes v0.5

Release Notes for Arbor v0.5

Added a library for I/O operations related to model descriptions to the C++ library
- SWC loaders for both Allen/SDK and NEURON styles #1190
The ability to query the names of mechanisms in a mechanism catalogue (C++ and Python wrappers) #1199
Documentation updates
- fix missing links
- more complex python examples in quickstart
Added support for using use-supplied Pybind11 and nlohmann/json libraries #1198 (PR under review: awaiting documentation changs)
Python wrapper extensions
- Full support for sampling API on python side
- placement interface for translation and rotation then querying of morphologies (PR under review)
Support for cable_cell read only interface and separate decor descriptions
STDP (PR up, being tested by partner)