initial look at setting filename pattern

[thebioengineer]

Looking at a way to allow users to set filenames. We need a pattern to then be able to look back and generate gifs.

This has not been tested, so use at your own risk right now.

new argument in gg_record - filename_pattern, which is "Pattern to use when naming the interim files. Must use one of the reserved camcorder iterators: {timestamp},{i}"