Add option to disassemble command to disassemble at a specefic address
Fix a small disassembly error
Allow idents to have periods in them
Refactor parser to store tokens being parsed in a linked-list

This is in preperation to adding pseudoinstructions and etc. The
linked-list allows tokens to be parsed again after they are recieved
from the lexer. This will be important when there may be multiple
possible routes, and we'll have to bail out of one and try the next.