Header cleanup

[lorenzncode]

No description provided.

[lorenzncode]

@dcowden confirmed it's ok to change the file headers to something like this:

# Copyright (c) CadQuery Development Team.
# Distributed under the terms of the Apache 2 License

Given this, I proposed to eliminate the header info outside setup.py, LICENSE files (currently the outdated header does not appear in every file - only a few select files). There was agreement on this too. This PR retains a header in the main cq.py.

I see @adam-urbanczyk has fixed the mypy issue in another open PR.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 95.33%. Comparing base (6b3b14a) to head (074870d).
Report is 3 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1732   +/-   ##
=======================================
  Coverage   95.32%   95.33%           
=======================================
  Files          27       28    +1     
  Lines        6788     6842   +54     
  Branches     1013     1025   +12     
=======================================
+ Hits         6471     6523   +52     
- Misses        193      194    +1     
- Partials      124      125    +1     

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[adam-urbanczyk]

LGTM, thanks @lorenzncode