Create a module to simplify creating activity-map movies for 2D populations

[apdavison]

Related to ticket:49, for 2D populations it would be nice to have a class/function which took a SpikeList object as argument, and produced a movie of the activity map, either as spikes (a flash for each spike) or as firing rate. Multiple formats should be available. I'm particularly interested in MPEG and FLV (Flash video, like YouTube).

Extending this a little, it would be nice to have movies showing several populations at once. For example, for visual system models, you could have several panels within the movie frame, showing simultaneously the stimulus, retinal activity, LGN activity and activity of each cortical layer.

I suspect several people might already have code that does some of this (I'm sure I have, somewhere on my hard disk). If you have, please put it in a file within the visualization directory and then we'll have some code to work from.

[apdavison]

ok, I've just noticed SpikeList.activity_movie(). This is a good start.

Needs to be generalized to allow plotting several SpikeLists in a single movie, and to soften the dependency on mencoder. For example, I have ffmpeg installed but not mencoder.

Should also allow plotting non-gridded populations.

[apdavison]

also just noticed plotting.save_2D_movie()