Implement retrigger properly for all oscillator types

[mkruselj]

Closes #3171

[mkruselj]

Questions for @baconpaul:

1. Should we add a very tiny quick fade-in for sine/FM2/FM3/window? It seems that WT osc has something that de-clicks its output even with retrigger off, so maybe others should match that?
2. Method to somehow set osc retrigger from the config.xml presets. Window, Sine, FM2/FM3 and WT should have it on by default when selecting osc type.

EDIT: After further thought, I've decided that 2. is not important. Let the users click the button...

[mkruselj]

Since clang-format did its thing to the codebase, and FM3 had some work done by @baconpaul which clashed with this PR, I am closing this one in favor of #3785 which is done from scratch.