Meta-phy LinkedList tests

[jay-tyler]

Make the test functions for tests_linkedlist.py accept functional arguments, these being either list or LinkedList.

There will be some organization effort here. Current idea is to do the following:

1. Have a constant at the top of the file that declares a functional constant
2. Mark all meta testing with a prependage like def test_meta_blahblahblah():
3. Use another file which imports regular tests_linkedlist, overwrites the functional constant, and runs the meta tests. The meta tests will ensure that the LinkedList api is fully congruent with the list api.