0.8.0

Rename classes and modules. Expose clip_accum.

• Exposed in top-level functions parameter clip_accum that controls
  whether or not to reset the list of "bad" (clipped out) sources after each
  clipping iteration during model fitting. [#169]
• Renamed modules and classes (with planned short deprecation period); [#170]
• Removed previously deprecated parameters. [#170]