* Added docs for the class. Override only buttonEvent (as for other non-visual editors)
* Started fixing other editors, a lot of redundant code can be removed.
* See comments in VisualEditor.cpp

this should work as very simple filter for one channel. The global var is shared between channels atm so it behaves weirdly on multi-chaannel data

very early alpha  -  this still has a lot of hardcoded paths etc.!