Fixed trailing labels
Added dw, rb directives
Evaluating inline expressions

Fairly experimental at the moment.
Oops
Bitwise operations supported for expression evals

Some minor refactoring as well.
Initial work on preprocessors

#define works for numbers
Include preprocessor added

Also cleaned up the tokenizer a bit.
Proper error messages

Also fixed my maggotry.
Rohan's breaking my code
Merge remote-tracking branch 'origin/Assembler'