Merge pull request #423 from diizy/stable-0.4

Triple osc: make buttons more visible (fix #306)
Merge pull request #427 from diizy/stable-0.4

Waveshaper, Dynamics processor: some code improvements
PianoRoll: don't play test notes while recording

This is a partial revert of 2e799718d621133103222e9d119d9443158ac4be.
As playing test notes generate MIDI events as well, they get recorded
like any other notes resulting in undesired behaviour.

Closes #368.
Projects: install sample project templates

Also install sample project templates in order to make the open-from-
template button usable per default.

Closes #425.
PianoRoll: renamed class and file name to match current coding style
SongEditor: renamed class and file name to match current coding style
GUI: improvements on icon graphics, missing updated setup dialog icons
Change icon of bb-editor window to one that fits better, also: remove add_controller.png which isn't used anywhere