[racket] unicode properties package

Per the suggestions of several folks (eli, robby) I've released a unicode-properties package that provides definitions for a few of the most commonly-used unicode properties (XID_Start, XID_Continue, and Bidi_Mirrored). Perhaps more interesting, it also contains code to automatically download the unicode database text files and extract definitions for other properties.  

If there are other binary properties that people think might be useful, please let me know and I'll add them to the default.

you can install this with

raco pkg install unicode-properties