Friendlier execution modes when running from Main.hs

Normal execution:
    mini-core file -> executes program, prints output
Verbose execution:
    mini-core --verbose file -> executes program, prints all intermediate
                                states
Step-by-step:
    mini-core --step file -> executes program, prints intermediate states
                             one-by-one. Type n for next state, q to quit.
Removing Test.core/Test.out. They're out of date
Add some examples
Adding cabal file; adding Makefile; restructuring files