use explicit helper method for sequence->ctuple coercion rather than calling generic SequenceNode.coerce_to()

Fix typo in sharing_declarations

Though this path is never taken for unsigned ints, MSVC still throws
warning C4146.

Add initial .mailmap file.

Not perfect yet, but it covers all committers with 10 or more commits.  I
didn't go looking below that threshold.

More complete cpdef enums.

Conflicts:
	CHANGES.rst

explicitly handle CloneNode in replacement transforms to make sure we take care of its content argument

Conflicts:
	tests/run/iterdict.pyx