* _7zz: correct license and remove p7zip dependency
The code under Compress/Rar* is licensed under a specific unRAR license
Also Compress/LzfseDecoder.cpp is covered by BSD3
The unRAR code is removed from the `.tar.xz` since the license posits you
agree or remove the code from your hard drive
This adds some complexity to updating 7zz so there is also an update
script
Meta has been updated and tweaked
Source is now downloaded from sourceforge in the `.tar.xz` version to
avoid depending on p7zip
* _7zz: add notice of the license updates and optional unRAR licenced code
