Change test to accept options, main to test multiple files

Change test to accept options, main to test multiple files

Change everything to make main merge input files (a little like paste).
This change is made to test bonus part - using get_next_line with
multiple files.
Move logic to produce correct files from test script to Makefile.
Create logic to enable testing of all(a), mandatory(m) or bonus(b)
parts.
Remove dependency on a function available only through get_next_line* as
that may (and probably would) be part of only my implementation. Add
functions that substitute this function.
Update .gitignore to ignore more temporary directories and files that
are created by running test script.
LOGIC FOR PRODUCING THE CORRECT OUTPUT FOR BONUS PART NEEDS TO BE
IMPLEMENTED IN THE FOLLOWING COMMIT.