Prototype Processor aSsembler

computer architecture[1] is by qubane[2];
assembler is by nakidai[3] and released in public domain

pros:
- factored out emit() function so it can be replaced with something more
  suitable for your specific use case
- case insensitive (except for filenames in includes)
- `inc' mnemonic that includes some other file
cons:
- doesn't handle comments very good, but still (start line with `; ' to make
  one)
- code is garbage a little
other:
- lda instruction uses atoi for number converting, hence number base there is 10
- register check is case insensitive by 1 letter, so e.g. ACC can be named as a,
  AcC, acC, AR etc

[1] https://docs.google.com/spreadsheets/d/1ESjhZcvpGmuHCNxgOESfSy-MXQoqrMqCyCDJyvDhRMM/edit?usp=sharing
[2] https://github.com/qubane
[3] https://nakidai.ru