Break label method into two methods.

register_label_statement handles the addition of labels to the current
unit, label simply parses.
Add comparison operators for value_t.
Shrink instruction set some more.

- Update comments for instructions and so on.
- Conditionals replaced with Lua-like EQ/LE/LT instructions. Only
  executes the next instruction if the condition is true.

Still debating whether LOGAND and such should function the same.
Add basic conditional blocks/statements to asm2bc.

Just makes working with the conditional instructions easier.