Don’t use ALLOCA_N
Simplify #space? documentation
Change UNICODE_ prefix to U_ for types
Change UNICODE_ prefix to U_ for break types
Change UNICODE_ prefix to U_ for grapheme and word breaks
Change UNICODE_ prefix to U_ for scripts
Change order of type names to put category before sub-category
Change break to line_break
Update definition of TYPE2ID/SCRIPT2ID
Prefix normalization modes
Remove unichar type and replace with uint32_t
Change types to general_category
Fix RMATCH_REGS test
Fix a -Wcast-align warning

I don’t know if this is OK, but I think it should work, considering that
bsearch() works similarly.
Fix a bunch of string format warnings
Fix a broken stub
Use const and pure attributes
Remove Type and _type suffixes
Add U::String#grapheme_break
Rename LocaleType to enum locale