[XeTeX] ucharclasses needs some help for XeTeX 0.99996

[Mike "Pomax" Kamermans]

With major thanks to Qing Lee for the PR that uplifts ucharclasses to 
work with 0.99994 and up, a new version of ucharclasses was released 
yesterday that should work with the most recent version of Xe(La)TeX. 
However, Werner Lemberg also filed a PR to add in Unicode 8.0 block 
support to v2.1, which I just merged in, so I will be spinning a v2.2 
and sending that off to CTAN later today.

- Pomax