Beginning of writing tests, one program written.
Using long instead of size_t, as it is the type used by the file libs.
Separated out file utils into separate files, for easier usage when testing functionality.
Further work on tests, incorporated some simple macros for testing use.
Sorted out Makefile again.
Made error messages a bit clearer.
Further clarification about what went wrong.
Renamed file which is just an out of bounds check.