Refactor so that it is easier to work with alternate MIME types databases, and programmatically extend the database in different ways.
Refactor so that it is easier to work with alternate MIME types databases,
and programmatically extend the database in different ways.

This closes the SF bug (feature request) #439710.

sk-/python2.7-type-annotator,sk-/python2.7-type-annotator,sk-/python2.7-type-annotator