Adds crash protection in the form of a pickle save after extraction/conversion/encode
Adds crash protection to the crash protection in the form of a .bak file due to nasty python/pickle bug (issue 23)
Merge branch 'develop' into feature/crashProtection
Checks each track's extracted or converted status before extracting or converting. After crash, will not re-extract or re-convert already done tracks.
Merge branch 'feature/crashProtection' into develop