Separate stepic-specific input handling

I created a stepic module to handle the Stepic-specific data file formats in a
generic way. Function split_content separates the Stepic-provided input files
into input and output portions if they're both there (sample data). If not,
the entire file gets treated as input (quizzes). check_output_vs_expected will
compare the output provided by Stepic against the output provided by your
routine. The routine should combine all of the answers with a space separator,
because that's how Stepic expects the answer.

The details of handling the output could also be moved into here, but haven't
yet been.
Modify find_clumps to work with Stepic module

Modify another program to use the simplified data handling allowed by the
Stepic module.