[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.

The functions should be inlined, otherwise it breaks with the headers
are used in multiple robots mode.

Set default initialization of variables + expose spatial quantities methods + correct bug

[C++] Build sample humanoid model with joint limits.

  * Velocity and torque limits are choosen randomly from the [0;1]
    interval for 1D joints.
  * Position limits are choosen randomly from the [-1;1] interval for
    1D joints.
  * Torque limits set to zero(6) for freeflyer joint.
  * Velocity limits are choosen randomly from the [0, 1e3]^6
    interval for freeflyer joint.
  * Position limits are choosen randomly from the [-1e3, 1e3]^7
    interval for freeflyer joint.