adding get_buffer helper function, moving slurp function location
basic slurp function added
converting some integers into size_t
removing manual buffer management, moving to get_buffer use, memory management now encapsulated in helper functions
moving source within Program type
removing unused defines
changing argument to allow for using length based strings, removing surplus strlens
adding implementation of parse_expected, fixing error around parse whitespace handling
implemented parse_byte
implementing parse_write
tidying up handling of quit case