* Put MakeGlyph back into FT*Font classes instead of FT*FontImpl, and make
it use as few FT*FontImpl members as possible so that external application
may actually have a chance to properly subclass us.
* Mass consistency renaming: the fonts' "FTGL" prefix is dropped in favour
of "FT" because all other types use only the latter.
* Rename "Extrd" types to "Extrude" because the former doesn't really make
much sense.
* Added appropriate #defines so that legacy applications still build.