First (untested) version of a 2d `TimedArray`
Document and test the new 2d `TimedArray`

Closes #112
Fix the handling of to big time values for 2d timed arrays in weave
Update travis.yml to latest miniconda version
Added NaN definition on Windows
Support for INFINITY and NAN in c++ standalone
Fix the "i argument out of range" check in the C++ implementation of `TimedArray`
Add a `TimedArray` (1D and 2D) test for standalone
Merge pull request #381 from brian-team/timedarray2d

Timedarray2d