Impr sugg: wave editor: right mouse button should "draw a line"

[GoogleCodeExporter]

The RMB should have a special function in the waveform panel: paint a line. Say 
if you want to draw a perfect saw, you'd press RMB in the top-left corner and 
paint to the bottom right, and all waveform values from left to right would be 
interpolated between the amplitude of the beginning of the click and the 
release.

Ideally, it would re-draw every time a mouse movement is detected, so you could 
have it "morph" in realtime and listen to it change when you change the line 
with the RMB pressed, while the song is playing.

Original issue reported on code.google.com by [email protected] on 17 Aug 2014 at 2:33