Support Guitar Pro 7 track volume#445

Merged

Danielku15 merged 4 commits intoCoderLine:developfrom

jordanske:feature/guitarpro7-track-volume

Dec 2, 2020

Commits on Nov 29, 2020

Commits on Nov 30, 2020

Simplified parser code, fixed Grace Beat test, and added new test and testfile for track volume
jordanske
committed

Commits on Dec 1, 2020

Added panning to the import and made a test for it
jordanske
committed