Create a version of RaspiVid where the frame rate of the camera can be controlled via IPC signalling to a running raspivid process.

1. Determine which of the USR signals sent by e.g. kill(1) are available for customization of this sort
2. Define signal handlers for raspivid that set the input framerate NOTE: it is preferred that the video stream not have to be reset when the frame rate is set while raspivid is running
3. Sequence:
4. capture frame
1. run initial frame analysis on first frame
2. save results
3. increment frame rate
4. loop