[check-*] Minor
Fix possible snprintf OOM

https://bugzilla.redhat.com/show_bug.cgi?id=1001645
[gtk-doc] Fix maintainer-clean rule
Minor
Improve check-includes.sh
Separate face source code from font

Makes documentation / introspection easier.
Add hb-deprecated.h, and rename a couple enum values

Add deprecated alias for old name.