Add a README section about contributing

Remove small optimization when parsing the input instruction.

Any instructions following INP were being ignored.

Fix instruction generation

Working well now.

Fix and improve LC3 compilation

Also improve Cargo.toml and add toasty LC3 VM primitives as dependency
main.rs is a test ground now, should be ignored.

Add reference to other LC3 projects

Improve cargo file, add README and license

Implement first PoC for LC3 backend

Tidy up code and prepare for LC3 backend

Add example programs

Implement initial prototype