Internal API redesign

[artivis]

This PR initiate a large cleanup of the internal API relying on traits to overload the different group/tangent functions for each derived. It cleans up the old API design debt where e.g. Derived::inverse hides Base::inverse. Going with this new design allows to more easily specialize functions where and if necessary. This will also (hopefully) open the door to,

• implementing left-jacobian as proposed here
• template expression (a la Eigen), altho that's not part of the foreseeable future

Comes on top of #147.

[codecov-commenter]

Codecov Report

Merging #150 into devel will increase coverage by 0.02%.
The diff coverage is 99.72%.

@@            Coverage Diff             @@
##            devel     #150      +/-   ##
==========================================
+ Coverage   98.23%   98.25%   +0.02%     
==========================================
  Files          37       71      +34     
  Lines        1130     1148      +18     
==========================================
+ Hits         1110     1128      +18     
  Misses         20       20