Add easter egg profiling window.
Fix displaying of empty sheets.
Send signal_module to refresh all views of module data.
Add album, song, pattern and column models.
Show sheet in main window.
Show contents of song 0 in the sheet.
Change octave selector into a QFrame.
Remove public ID access from models.
Add pattern instance model, render all tracks in the sheet, clean up interfaces.
Give patterns to the sheet ruler instead of pattern lengths.
Add trigger representation to the model and update Column to use it.
Update sheet scrollbars when pattern data changes.
Fix style.
Add trigger position object to the model.
Add selection object to the model.
Integrate selection to the rest of the model and display the selection in the sheet.
Clean up cursor drawing code.
Add update callbacks to sheet ruler and view, fix an incorrect assert.
Refer to the utils module of the sheet by its name instead of importing all.
Make cursor position calculation more generic for cursor movement code.