- Add `.extern` directive allowing the user to define external labels
- Add `.scope` for `.def` and `.de.` variables
- Add `#cop n, ...` preprocessor directive. It should work just like .rep but just insert the line n times into the source code and then preprocess the result.
+- Add function calls to expressions. For now only hard-coded functions such as MIN and MAX should be added.
+- Add bank number to label struct
+- Add a BANKNUM function e.g. BANKNUM(label)