Remove music slot compatibility

Remove support for music slots, it's deprecated and is another thing that should have been killed for 2.2.0. Plus another branch I'm working on depends on it being removed anyways.

added 1 commit

• 83e80eef - Add deprecation warning when using the level header parameter

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#379 (closed) is related

merged

mentioned in commit 186ef047

changed milestone to %2.2.10

removed milestone

changed milestone to %2.2.10