Created new Group._set_with_code_conditional will be needed for
standalone mode, works in runtime but not used automatically, doesn't
work in standalone because _array_i is not defined
Start simplifying the indexing system. This commit only affects NeuronGroup (including subgroups), Synapses are broken.
Make synapses work for the most part, some issues with subgroups still
Fix a bug in synapse creation, test suite now passes
Merge latest changes from the devices2 branch
Merge latest changes from the devices2 branch
Start on making group_variable_set_conditional work -- currently subgroups are broken, though.
Add a read-only attribute for Variable objects
Add an `arange` function to devices that creates an `ArrayVariable` filled with numbers from 0 to size-1. This will be used for the variable "i" in a `NeuronGroup`.
(yet another) major overhaul of the indexing system, Synapses not quite working yet
Making progress with a Subexpression-based approach, but not quite working yet (Python-only currently)
Merge remote-tracking branch 'origin/index_refactoring' into index_refactoring

Conflicts:
	brian2/groups/group.py
Adapt PoissonGroup to the new indexing system
Test suite passes for Python
Still struggling with types, templates, etc.
Merge remote-tracking branch 'origin/index_refactoring' into index_refactoring
The test suite passes!
Make cpp_standalone work (including variable initialization)
Remove templates that have become unnecessary
Fix the "levels" value for the local namespace