Various improvements

[fspindle]

• Add PCL defines for doxygen doc
• Improve doc
• Make Panda3D available only if c++11 or higher
• Fix build when c++11 and realsense
• Upgrade pugixml from 1.9 to 1.14

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 45.29%. Comparing base (504583e) to head (0baca3e).
Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1444      +/-   ##
==========================================
- Coverage   45.30%   45.29%   -0.01%     
==========================================
  Files        1108     1108              
  Lines      110137   110137              
  Branches    18874    18874              
==========================================
- Hits        49895    49886       -9     
- Misses      60242    60251       +9     

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