mpm: Clean up code, improve Pylint score

Many small cleanups:
- Fix copyright headers
- Fix superfluous imports
- Pull some constants out of classes where appropriate
- Fix formatting
- Improve/fix some docstrings
- Disable specific Pylint warnings where appropriate
- Global catches use BaseException instead of Exception
- Don't use len() for empty checks
- Make sure to declare all self attributes in __init__ (note: this is
  particularly of interest for E310, becuase its regular init happens
  outside of __init__)
- Compacted some E310 code that had multi-DB checks

0 files changed, 0 insertions, 0 deletions