Add numbers in index.
Fixed: if an entry is changed in matrix recalculate inverse and transpose (if necessary)
Changed: added formatting in printing of matrix so that it looks nicer.
Made the filter into an iterable object.
Added first Kalman Filter implementations.
Merge branch 'master' into docs.

Need to update docstrings in branch docs so that I can generate a new sphinx
documentation.
Big docstring changes in matrix.