Added __name__ == '__main__' bit to prevent scratch code from being executed during testing.
Two tests still failing. Need to fix those, refactor and document.
Looks like I'd overlooked some options. The test was missing entries in this case.
Checked test and it is correct. However, the code is generating D5 entries for G6 for some reason.
Added tests to find out where D is coming from instead of G6, but no luck.
Fixed bug in note2fret function. Notemappings module appears to be pretty much complete, just clean it up now.