[Fluxus] new feature

[gabor papp]

thanks for the comments. i merged scratchpad-effects into master.

there are 3 effects implemented as shown in the video: jiggle, wave and 
ripple. i added a scratchpad-effects.scm to examples in which you can 
see the parameters.

feel free to add more effects to GLEditor::Render or rename the current 
parameters if they don't make sense.

the effects can be switched on and off with f9.

best,
gabor