Build the speedup C-extension against the stable API. This is done by emulating PyUnicode_New()/PyUnicode_WriteChar() with encoding the UCS4 character to UTF-8 and using PyUnicode_FromStringAndSize().

include .hg* *.txt requirement*
include configmix/*.c
graft docs
graft tests
prune docs/_build
global-exclude *.pyc *.pyo