Added graph.breadth_first_search() and test function.
Added graph_main.rs and made sure it compiled.

Moved the DFS/BFS closure functions inside of
the corresponding test functions.
Forgot to add graph_main.rs.
f_heap.rs - Compiles and passes meld test.
Added delete_min(). Passes delete_min test.
Changed FHeap to take and return key/value pairs.
Added FibEntry type.
Added decrease_key() and passed test.
Added delete() function and passed test.
Added cascading_cut() and pass test.
Changed FibEntry representation and actually pass tests.

Ignore all previous commit messages saying tests pass,
those actually only mean that the file compiles. I
foolishly forgot to run the compiled test executable
to ensure that the tests passed during runtime.

The FibEntry representation was changed from RefCell to
unsafe ptr's because the RefCell would not allow me to
have mutiple references to the same mutable memory location
active at the same time.