Using dask to save frames in parallel

I am opening a separate issue for this functionality (previously mentioned in #2).

Currently the most time intensive step in creating a movie/gif is the rendering of each frame, which is done in serial.

In an earlier test version I implemented a parallelization of the printing using dask. The speedup was very nice, but I encountered quite strange errors with some matplotlib elements: E.g. the colorbar label would shift around and other odd things that looked less than premium.

I would like to try to implement this again with the substantially refactored code. The proposed changes would replace the default save_frames with save_frames_parallel if a dask array is passed, so that mov.save(moviename.mp4) would work in parallel out of the box and serial rendering could be forced with something like mov.save(moviename.mp4, render_parallel=False).

[dcherian]

Map_blocks works really well

[jbusecke]

Its here: https://github.com/jbusecke/xmovie/tree/jbusecke_dasksave, but use at your own risk! It is quite old at this point!