Even though we use collections.abc.Set which implements all these
methods under their operator names, the actual named variations of
these methods are shockingly missing. So let's add them manually.
Another fix to the docstrings, this time for the English part of the
docstrings, not the Python class name. No functional changes here.
Signed-off-by: Daniel Kahn Gillmor <dkg@fifthhorseman.net>
This moves away from the deprecated notmuch_database_add_message API
and instead uses the notmuch_database_index_file API. This means
instroducing a class to manage the index options and bumping the
library version requirement to 5.1.
