Brain.save_movie() II

Alternative to https://github.com/nipy/PySurfer/pull/79 co-opting `Brain.make_montage()`

I feel like this multitude of options, combined with the `rol, col` arguments below makes this signature quite complex. Can you add an `Examples` section to this function showing all the use cases you're trying to accommodate here? Hopefully there's a simpler way to do it, but if not, at least introspecting editors will show some ideas when looking at this function so users don't have to find the example file.