Add gmgpolar namespace

[EmilyBourne]

Merge Request - GuideLine Checklist

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As many checkboxes as possible should be ticked.

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Always to be checked:

• There is at least one issue associated with the pull request.
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• Tests for new functionality has been added
• A local test was succesful

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• Did you pay attention to its license? Please remember to add it to the wiki after successful merging.

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• Are new methods referenced? Did you provide further documentation?

Checks by code reviewer(s):

• Is the code clean of development artifacts e.g., unnecessary comments, prints, ...
• The ticket goals for each associated issue are reached or problems are clearly addressed (i.e., a new issue was introduced).
• There are appropriate unit tests and they pass.
• The git history is clean and linearized for the merge request. All reviewers should squash commits and write a simple and meaningful commit message.
• Coverage report for new code is acceptable.
• No large data files have been added to the repository. Maximum size for files should be of the order of KB not MB. In particular avoid adding of pdf, word, or other files that cannot be change-tracked correctly by git.

[julianlitz]

Putting everything inside a namespace is a good idea.
Feel free to use GMG:: if you like to or gmgpolar:: depending of what you like best.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.70%. Comparing base (918f0a5) to head (e015040).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #215   +/-   ##
=======================================
  Coverage   90.70%   90.70%           
=======================================
  Files          86       86           
  Lines        9454     9458    +4     
=======================================
+ Hits         8575     8579    +4     
  Misses        879      879           

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[EmilyBourne]

Putting everything inside a namespace is a good idea.

I had problems linking GMGPolar to gyselalib++ mostly due to Vector which is a common name across many code bases.

Feel free to use GMG:: if you like to or gmgpolar:: depending of what you like best.

I have no strong feelings about the name. I chose gmgpolar to reflect the project name but maybe this is sometimes used for an instance of the GMGPolar class?