* new utf8proc_map_custom for hooking in user-defined custom mappings
* whoops, add test program
* NEWS, version bump for 2.1
* change test functions to static so that gcc doesn't complain about missing prototypes
* Updates for Unicode 9.0.0 TR29 Changes
- New rules GB10/(12/13) are used to combine emoji-zwj sequences/
(force grapheme breaks every two RI codepoints). Unfortunately this
breaks statelessness of grapheme-boundary determination. Deal with
this by ignoring the problem in utf8proc_grapheme_break, and by
hacking in a special case in decompose
- ZWJ moved to its own boundclass, update what is now GB9 accordingly.
- Add comments to indicate which rule a given case implements
- The Number of bound classes Now exceeds 4 bits, expand to 8 and
reorganize fields
* Import Unicode 9 data
* Update Grapheme break API to expose state override
* Bump MAJOR version
