BUG: Fix commutativity of {dot,multiply,inner}(scalar, matrix_of_objs)

Fixes #2469 and #4482. Relaxes fail condition to allow subtype as documented.
DOC: Add backport of gh-4483 to release notes.
Merge pull request #4501 from charris/backport-1.8-gh-4483

Backport 1.8 gh 4483