Got a re-designed test script to run.

Tweaked the Python and C drivers a bit:

- Always include the size prefix, C decompression is hard without this.
- Don't add/subtract 1 to the size.

I guess I should figure out if it's possible to determine from a compressed stream if the size prefix is present.
Renamed old testrunner to testfile, to clarify its role. Created new wrapper script.