fixes an issue with negative scale in mixer fill commands. it now does what one expects, namely reflects the image.
Updated CHANGES.txt
Introduced paused OSC message for a layer
straighten alpha before applying contrast-saturation-brightness when contrast is less than 1 and remultiply afterwards to prevent rgb values from rising above alpha value for each pixel.

#140
Consider a layer paused only if explicitly paused
Added support for mixer commands to return current values

#141
Make ffmpeg producer send osc messages while at eof.