Update matfaust.Faust.factors to handle BSR matrix retrieval (converting it to...

Update matfaust.Faust.factors to handle BSR matrix retrieval (converting it to a sparse matrix because matlab doesn't support BSR matrices).

- Add Transform(HelperGen)::is_fact_bsr
- Rewrite FaustSpMat2MxArray mex function to handle float and complex cases (in addition to double type). When a MatSparse float is converted to mxArray it is also converted to double precision because matlab does not support float precision for sparse matrices.
- Other minor changes.