Optimize index generator
More precision annotations in shader generators, other microoptimizations
Revert "Merge pull request #4068 from bollu/AudioArtefactFix"

This reverts commit e4c6ba9b01e2ca2d6faf7465ae579d4313408776, reversing
changes made to 061efd35dbd61f3a083bf315a57ab4a9d8f0e5be.
Revert "Merge pull request #4021 from bollu/master"

This reverts commit c84a9daa40e07e5f65418c12f9d5d99ce58298df, reversing
changes made to da5b52ce1fb3c4b1c0c8661e69d996678bc8961b.