Use binary-search for finding name table entries

VotoSerifGX has over 500 named instances, which means it also has over a thousand
name table entries.  So we were looking for names for over 500 pattern, looking for
some thirty different name-ids, and using linear search across the 1000 entries!

Makes scanning VotoSerifGX three times faster.  The rest is probably the lang
matching, which can also be shared across named-instances.  Upcoming.
1 file changed