Fix SpikeMonitor's update of the total per-neuron spike count in C++ standalone
Add some small absolute tolerance to the parsing test for expressions that evaluate to 0.
Use `char` to store boolean values in C++ standalone. Fixes #317
Only calculate `i` in subgroups with a subexpression if there is actually a non-zero value to subtract (i.e. not for subgroups at the beginning of a group)
Fix the loading of some constant, read-only state variables (e.g. `N_incoming` in `Synapses`) in C++ standalone.
Merge pull request #319 from brian-team/bool_as_char

Bool as char
Ignore Brian preferences file in examples folder
Small change to CUBA example
Document the new time/dt/scheduling system (as if it were already implemented)
First steps towards the new scheduling system
Most problems fixed (except: recording from subgroups, changing dt for spikequeue)
Fix monitors (no need to use the source's clock, monitors can use their own clock)
Fix an overwritten `dt` attribute in `SynapticPathway.initialise_queue`
Use the floating point value of dt, not the `Quantity` as the key for the dictionary in `_determine_clocks` -- otherwise it won't work in Python3
Update some more tests to work with the new clock system.
Make sure that the order of objects in a `Network` is deterministic, even for arbitrary orderings (same dt, when and order attributes).
Don't hide failed `get_value()` calls in `AttributeValue` when transforming the variables dictionary into the final namespace.
Adapt the test that refers to `t` with a 0ms run to make sure that a clock exists.
Partly revert previous changes, establish the new clock/dt system as discussed in #318
Disallow setting `Network.t` directly.