While support for tagged pointers was merged in [](b4039f9a85), they are only being used by OFNumber and OFDate right now. It would be nice to also use them for short OFStrings. This requires a new OFString subclass.

Since most short strings will be ASCII, tagged pointer strings can be limited to ASCII strings, requiring only 7 bit per character. This would allow storing up to 8 characters in a tagged pointer on 64 bit systems (even when increasing the tag size to a full 8 bits) and up to 4 characters on 32 bit systems (but the tag size needs to stay at the current 4 bits).