[jpaxwgia] Pipeline infrastructure for animations

An application writes to a canvas.  The canvas may be virtual, and what happens to the output is outside of the application's control.

It may be simply draw the animation or video to screen (like the text program "cat"), or piped through a separate program allowing pause, rewind, and playback (like the pager text program "less"), written to a file (like ">" redirection), or manipulated in arbitrary ways, say size or rotation, etc, (kind of like the program "perl").

This is simple, decomposing the physical viewing into configurable steps.  (DRM of course hates this.)

There is no input through the canvas; it must come through another route: perhaps a separate application transparently overlaid on the output.