* Further restructuring

* Rename library to `emulator_2a_lib`

* Begin core rewrite.

- Copy `machine` to the library.
- Redo/Comment/Test `register.rs`.
- `register.rs` still lacks the utilities to work with the other components.

* Continue rewrite

* Finish directory structure and fix all errors

* Finish basic assembly of parts

The bulky rewrite is done. Now the api needs cleaning, the code seperation and everything needs more tests and documentation.

* Implement and seperate Machine/Interface api

The MachineInterface serves as a higher level api to the raw Machine.

* Further library extraction

* Further library extraction

- Updated all binary deps
- Removed machine stuff from binary
- Moved compiler to library

* Document compiler and define default stacksize

* Add some tests for the ALU

* Add ascii graphic to mr2da2 doc

* Make interrupt source part of correct register

This only alters internal behaviour of the extension board.
Also did some commenting and formatting.

* Add some contribution information