Refactor Filter and Filter routing computation.

 - Builder has no responsibility for managing filters on vertices.
 - Temporary methods `n_filters`, `n_filter_routes(subvertex)` added
   to provide information to system region.
 - `FilterCollection` removed.
Remove unnecessary line from Makefile.
Refactor of filter/routing loading parameters.

 - Number of filters/routing entries is 1st word of respective regions.
 - One function each for mallocing and copying in parameters.
 - Matching changes in Python.