Add Makefile
Spelling error correction
Add unit test to ensure check_recursion_depth raises error
Add todo note about a limitation in reference to path

Reference to path is currently detecting classes as functions and
failing because they do not have the same attributes.  The logic
that determines the type of reference needs to be made more robust.
Correct reference to path's handling of classes

Correct reference to path so that the path to classes is correctly
returned.