DOC: add minimal clarification to the matrix.ravel docstring
MAINT: fix the import
MAINT: restore optional ravel order and add tests and more docstring lines
DOC: clarify that matrix.ravel only copies if necessary; this is already tested
MAINT: use N.ndarray instead of core.multiarray.ndarray
Merge pull request #4932 from argriffing/ravel-docstrings

DOC: clarify matrix.ravel docstring and add tests