[yt-dev] Issue #1096: [experimental] Change `clip_ratio` to something more descriptive and set to default use (yt_analysis/yt)

[Cameron Hummels]

New issue 1096: [experimental] Change `clip_ratio` to something more descriptive and set to default use
https://bitbucket.org/yt_analysis/yt/issues/1096/experimental-change-clip_ratio-to

Cameron Hummels:

`clip_ratio` could be changed to something more descriptive (stddev_mask?), and should be defaulted to something like 4.0 since it is used almost everywhere to produce useful images. kwarg instead of arg