[C++][CMake][Doc] Split geometry parser into two parts.Added guard to file to avoid multiple redefinition

[C++][Python] Reworked the geometry parser ( BuildModelAndGeom). Suppressed the duplicate code in parseTreeWithGeom : the geometry model is now built in a second loop over the urdf tree. Also exposed the <model, geometryModel> construction

[CMake][Python] Exposed GeometryModel and GeometryData in python. Little reworked of the headers_variables in the cmakelists

[C++][algo] algorithm updateCollisionGeometry now optionally executes algorithm geometry to compute positions before updating collision objects's positions

[C++][Geom] distances results for computeDistances is not always cleared but replaced by a vector with empty results. The initialization of collision pairs is now  always done in constructor.

[benchmark] Added benchmark of atomic computations with geometry objects such as updating global positions, determine if two objects are in collision, or compute the distance between two objects

[C++][unittest] Added unittest geom.cpp . It tests that we obtain the same results between Pinocchio and hpp-model-urdf for joints and geometry objects positions ; for collisions and distances between two geometry objects

Add unaligned prismatic joint + minor modifications

Fix bug when parsing urdf file model by considering free floating joint

Still cleaning the parser + add tool

[C++] Raise exception when inertia information is missing when build tree with a specific root joint

Functions defined in headers urdf.hpp and jacobian.hpp are set to inline.