Turn char arrays into fixed-length strings
Evaluate the -1 on array upper bounds
tk: Rename tkGetIdOrKw() -> tkSpellId()
c/cpp: Use tkSpellId() instead of tkGetText() where possible
tk: Add unified tkSpell() functions
cpp: Fix cppMain()'s #define body skipping
cpp: Re-implement token merging

based on re-lexing the concatenated text representations of the two
tokens, instead of merging tokens manually.
cpp: Support unsigned values in #if expressions