Merge pull request #615 from gabrielebndn/topic/mergedoc

cmake

doc/Doxyfile.extra.in

doc/Overview.md

doc/a-features/a-spatial.md

doc/a-features/b-model-data.md

doc/a-features/c-joints.md

doc/a-features/d-model.md

doc/a-features/e-lie.md

doc/a-features/f-kinematic.md

doc/a-features/g-dynamic.md

doc/a-features/h-frames.md

doc/a-features/i-geometric-models.md

doc/a-features/intro.md

doc/a-features/j-analytical-derivatives.md

doc/a-features/k-automatic-differentiation.md

doc/a-features/l-python.md

doc/a-features/m-tests.md

doc/a-maths/geometry.md

doc/a-maths/kinematics.md

doc/b-examples/a-model.md