Python interface: Renames methods to match PEP8 style

[francocipollone]

🎉 New feature

Related to #101 #210

Summary

• Python interfaces for Vector2, Vector3,Vector4,Angle,GaussMarkovProcess and Rand classes to match PEP8 style.
• Use rename SWIG directives to rename methods when creating the python bindings. (Aligned with PEP8 specification.)
• Python and Ruby files were moved to different folders in order to have for each language different SWIG files given that between languages probably the .i could change a bit.
  • For example: For the particular case of renaming, for Python we need to rename the methods but that's not the case for Ruby.

For reviewers

I suggest to review commit by commit:

• Use separate folder for ruby and python swig files and tests … --> c0e8e6d
• Renames python interface to match PEP8 style … --> a419f3c
• Update python examples … --> c54755f

Checklist

• Signed all commits for DCO
• Added tests
• Added example and/or tutorial
• Updated documentation (as needed)
• Updated migration guide (as needed)
• codecheck passed (See contributing)
• All tests passed (See test coverage)
• While waiting for a review on your PR, please help review another open pull request to support the maintainers

Note to maintainers: Remember to use Squash-Merge

[codecov]

Codecov Report

Merging #226 (dc50c48) into ign-math6 (cf5e33c) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           ign-math6     #226   +/-   ##
==========================================
  Coverage      99.21%   99.21%           
==========================================
  Files             65       65           
  Lines           6089     6089           
==========================================
  Hits            6041     6041           
  Misses            48       48           

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[LolaSegura]

Nice job, LGTM!

[francocipollone]

We could use one more review @chapulina @scpeters . 😃 🙏
Even though there are many lines in the git diff, the real changes aren't so many. Reviewing commit by commit is the suggestion.

Once this PR gets merged, the open PRs that add python interfaces for more classes should be updated. CC: @LolaSegura @WagnerMarcos

• Adds python interface to RollingMean, Color and Spline #218
• Adds Line2, Line3, SignalStats, Temperature python interface #220
• Adds python interface to Quaternion, Pose3, Matrix3 and Matrix4 #221

[scpeters]

I tried running pylint on the generated ignition/math.py file and it still complains about method names that are fewer than 3 characters in length. The following are complaints about the Vector4f class:

C:1108, 4: Method name "x" doesn't conform to snake_case naming style (invalid-name)
C:1111, 4: Method name "y" doesn't conform to snake_case naming style (invalid-name)
C:1114, 4: Method name "z" doesn't conform to snake_case naming style (invalid-name)
C:1117, 4: Method name "w" doesn't conform to snake_case naming style (invalid-name)

I think we can ignore this though