Add examples

[godotalgorithm]

Resolves #268 and #272. The /examples directory contains examples for both standard, command-line usage of MOPAC and the C and Fortran APIs. It is also packaged into the installer.

Status

• Ready for merge

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 69.44%. Comparing base (d564293) to head (2b24cef).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #303      +/-   ##
==========================================
- Coverage   69.44%   69.44%   -0.01%     
==========================================
  Files         339      339              
  Lines       76104    76104              
==========================================
- Hits        52850    52848       -2     
- Misses      23254    23256       +2     

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