Add a "conditional write" attribute to variables annotated with "unless refractory"
wrote some code to use .take instead of [] in numpy code, but left it
commented for the moment, cf: http://wesmckinney.com/blog/?p=215
Added CUBA example from Brian 1
Some progress towards conditional_write mechanism in numpy, but still
plenty to do

Current status:
- dev/ideas/conditional_write.py works
- 2 tests fail, but this isn't surprising because refractory behaviour
has changed
- 9 tests have errors, with _presynaptic_idx and _postsynaptic_idx
Move the addition of "conditional write" variables to the variables dictionary into `create_runner_codeobject`.
Remove a direct assignment to `_postsynaptic_idx` in the template which is no longer necessary (and was overwritten later, anyway)
Read in indices and arrays in the correct order in the generated numpy code (fixes the errors for `_presynaptic_idx` etc.)
Deleted some out of date scripts
Working version of conditional_write with reset override

Summary of changes:
- override_conditional_write argument is added everywhere
- reset uses this argument
- refactored some conditional write code into base Language
- implemented weave version
- fixed bug in numpy version where it would only work for 1 neuron
(because newly created variables weren't handled correctly), this wasn't
an issue for the weave version
- created new test of the behaviour
- changed the standalone test, because the new refractoriness mechanism
changes the results
Test conditional writing under weave as well
Remove some unused imports
Merge pull request #211 from brian-team/conditional_write

Conditional write (variables marked as "unless refractory" cannot be changed during refractoriness, e.g. by synaptic input)