Qtfaststart2

- Readme updates, skipped a few versions here because of an accidental mess-up with PyPi publishing

- Fix import errors by renaming everything from qtfaststart to qtfaststart2

- Fix: Exit gracefully on already optimised files. See https://github.com/danielgtaylor/qtfaststart/pull/17

- Support files with multiple mdat atoms. qtfaststart2 can mistakenly handle files with multiple mdat atoms as already
set up when the moov atom is actually at the end of the file. This patch makes certain the moov atom is placed before
all mdat atoms. See https://github.com/danielgtaylor/qtfaststart/pull/19

- Create qtfaststart2 which is branched off from [danielgtaylor/qtfaststart](https://github.com/danielgtaylor/qtfaststart)