[C++][Python] Added algorithm working with joint configurations ( integrate, differentiate, interpolate, random, uniformlySample, distance), their python bindings and unittest

Added missing licenses, corrected compilation bug in python/parsers.hpp. also modified the number of benchmarks to have more relevant results and removed useless lines

[bench][unittest] Reworked the comparison test between pinocchio and hpp : more tests for benchmarks along with functional tests ; removing magic paths to urdf models + modification of romeo urdf model. Also added a specific BUILD_TESTS_WITH_HPP cmake variable. If you want to run tests that execute hpp robot loading, be sure to have the package romeo_pinocchio installed (it is just a package done done by hand for the moment)

[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

[cmake][C++][bug fix] Moved initialization of static const variable gravity 981 from model.hpp to model.cpp. libpinocchio.so is no more empty. Caution : Pinocchio is more a header-only library. One should alwais link against shared library

Revised the unitests, added some doc and created a "check" compilation rule. All unitests passed ok.

Adapted both the urdf parser and the romeo model to enable romeo inside pinocchio. CAUTION: Romeo is not standard any more and should be corrected, by enabling fixed joint in the urdf parser.