TODO list for pre-final version.

[Haliris]

• [x] Test environment variables

• [x] Expanding variables within strings

• [x] Garbage collection refactoring for our main data structures (lexer, parser, here_doc)

• [x] Finish the built-ins

• [x] The functions themselves

• [x] Their implementation within the program

• [ ] Write a test script to check that runs agreed upon commands to check quickly that everything still works.

[Haliris]

REALLY check exit built_in behavior in bash.

Exit works fine with numbers signed with + but not with + alone for instance.

[BenjaminHThomas]

done :^)