Graphical convolution animation

Shows graphically the various stages of discrete convolution for any two 1-D signals.

This is for educational purposes really so the screens are optimized for signals of a few samples. Between two stages the figure pauses and requires the user to strike a key to continue. This should allow instructors to move on their own pace. Otherwise the user can enter the duration of the pause as an input.

The frames are also stored in case the user wants to make a movie or gif animation

Instructions for instructors are given at the end of the mfile.