Undo System Implemented

Hello!

Time for another update.

New features:

• Undo system! It might not work on all objects yet since it requires some extra work to enable it on each class
• Easier to edit the render matrix in the treeview
• Some support for Ctrl-O for opening stuff. Not working that well yet though..
• Possible to edit discrete fig line mod pattern conditions
• Voice oscillators now support randomize start value features for noise types
• Chord progressions generated with templates are now much more readable
• Upgraded to .NET Core 3.1. Not something that anyone will notice though :)
• Demo control window is now always on top

Bugfixes:

• Tie notes fig line mod now works again
• Grace notes fig line mod now works again
• Fixed a nasty delete button bug
• Changing names of destinations and sources in the modulation matrix now updates correctly
• Fixed a float range bug that somehow also changed how the default template song sounds
• Tab index for render targets and phrases are now separated

Breaking changes:

• The song file format changed

Bye!