Add initial playback support through calfbox. Still with hardcoded paths and no module integration. Don't use this commit
wip playback
Calfbox is now exxpected to be a global python module. Laborejo now works as before with command line parameters. Only with calfbox
Internal soundfont support and qt cmd parameter
Add small gpl soundfont as default
Use the internal soundfont
Begin playback at the correct position, even with a repeat section in between
Correct playback positions even when the original item was replaced by a trigger/empty combo
Handle playback start when the cursor is in a muted track or in the master track