Backport of some changes from master:
Minor textual changes:
GRAMPS > Gramps
place_displayer > _pd
__object_ > __media_
object_parse_tbl > media_parse_tbl
__find_object_handle > __find_media_handle
__find_or_create_object > __find_or_create_media
build_media_object > build_media
and a few pylint related spacing changes
Sorting of Sources bug9475
Change "class xxx(object)" to "class xxx"
Use "with open" instead of "try: except:"
change "raise NotImplemented" to "raise NotImplementedError()"
92d2181621