refactor: LabelMatrix now relies on pandas.DataFrame
refactor: LabelMatrix uses panda.DataFrame constructor
test: LabelMatrix
fix: Cooccurrence no longer exists (use get_cooccurrence_matrix instead)
refactor: going back to pandas.DataFrame composition for LabelMatrix
test: add test for get, set, remove_row, remove_column and subset
fix: TVTParser now relies on new LabelMatrix API
fix: mapping algorithms should use new LabelMatrix API (passes unit tests)
Merge branch 'feature/matrix_pandas' into develop