All mnemonics implemented for lasm.

1. Minor fixes to allow for implicit multibyte mnemonics
2. Fixed a switch fall-through bug
Fixed windows _toupper nonsense.
Fixed remaining r16|i16 typos
Merge pull request #16 from rdnelson/msvc10

All mnemonics implemented for lasm.
Fixed indexed addressing mode, cleaned up source representation
Merge branch 'master' of github.com:hasithvm/lasm

Merging @rdnelson's commits into main
Fixed register-indexed modes, suppress file generation on errors