new global variable $quiet
we use global for this to allow toggle by local $quiet++
which resets when the subroutine returns.
mixoff mixdown mixplay remove_track_cmd: transition to global $quiet
convert do_something('quiet') to { local $quiet = 1; do_something() }
seems fine.
Merge branch 'quiet' into undo
stealth autosave during process line() if engine isnt running
Bus::new() uses $quiet global
debugging
change order of initializing classes to avoid warnings
dev config
undo: reload project after commit rollback
update object sort orders for serializations
move subs, undo/redo works