[C++][Bug fixed] Changed from assignation to initialization...

[hotfix] Changed from assignation to initialization for a matrix in symmetric3 that causes computations errors with ubuntu 14.04 in release mode.

Topic/joint dense

[C++]{Minor] Changed the name of the method to access the segment of a given vector. The length of the returned segment depends on the dof of the joint(size NQ or NV)

[C++][Major] Reorganized the methods to acces segments of fixed size (one for NQ, one for NV) from joints indexes

[C++][Major] Added JointModelDense and JointDataDense. Both templated by the dimension of configuration space and tangential space. Each joint can be converted to a Dense one

[Fix Bug] Check norm of the vector to exponentiate

topic/crtp - Convert all current structures to the CRTP template

[Major][C++] Renamed macro for spatial traits : 2 cases -> use in templated/not templated classes to avoid polluting warnings. Following these naming could avoid multiple definitions of macro SE3_JOINT_TYPEDEF

[C++][Major] MotionRevolute is now CRTP. Moved out of struct JointRevolute to solve namespace problems

Conflicts:

	benchmark/timings.cpp

[Major] BiasZero is now a MotionBase (CRTP), implemented in jointrevolute. Switch in other joints to come

[Major] spatial class SE3 is now CRTP. Move traits class in spatial/fwd.h as it is now used in spatial classes and joint-base

Added two minor functionalities in the python bindings

[Python] force the computations of all coefficient in the mass matrix, in the binding of computeAllTerms.

Build library only if sources are detected.

Compilation with qcc for QNX