PyDict_UpdateFromSeq2(): removed it.
PyDict_MergeFromSeq2(): made it public and documented it.
PyDict_Merge() docs: updated to reveal <wink> that the second
argument can be any mapping object.
has grown beyond what font-lock will work with using the default (X)Emacs
settings.
Indentation of the description has been made consistent, and a number of
smaller markup adjustments have been made as well.