Fixed a couple of minor things
[[ Unicodify ]] Allow various unicode characters to be part of identifiers
[[ Unicodify ]] Update script point methods to be surrogate-pair safe
[[ Unicodify ]] Update all changes to script point's current pointer to use proper advancing method
[[ Unicodify ]] Do token table lookup with cstring to avoid converting every table entry to stringref
[[ Unicodify ]] Explicitly cast unichar_t to uint2
Modify some comments
Merge pull request #507 from runrev/refactor-syntax_unicode_script_point

Refactor syntax unicode script point