Harmonicon: Dropping the 3D View

I honestly love the 3d view of harmonicon, but it’s just eye candy. The amount of lines of code is exceeding 75.000 so I took the difficult decision to remove it, so I can focus on more important tasks.

I believe that harmonicon currently is the best harmonica song editor that exists, and removing some eye candy helps me focus on what it actually needs: polish and bugfixes.

That’s all.