Add attributes in model.hpp
	- names of fixed body
	- indexes of their closer movable parent
	- visuals booleans
	- number of fixed body
modify display method in robot_wrapper
	- compute and send the absolute placement from relative to the closer movable parent

To do so, added a new parameter ( placementOffSet) which enables to propagate the length of a fixed body to child joints  and edit the urdf tree to remove bypass fixed link when encountered and handled.

The fixed links are not displayed in the viewer yet and not saved in model yet

Follow the advice of gcc by casting directly with the proposed
CoeffBasedProduct template.
Makes gcc happy.
This patch was initially proposed by Florent Valenza but
with another type.

There is still an issue on ConstraintXd.
This commit *does not* compile is here for book-keeping.

[Major] Now handle prismatic joint when parsing urdf. Only cartesion X,Y or Z are accepted, unaligned axis bring crash

[Major] Correction of bugs in JointRevoluteUnaligned and its unittest. The urdf parser nows takes into account this joint. Added a new enum in cartesian axis

Conflicts:
	src/multibody/model.hpp
	src/multibody/parser/urdf.hpp

[partial cherry-pick from b87a2b53b3]

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.

Warning remaining at compilation of CRBA.
Timings:
nq = 36
RNEA = 		4.79756 us
CRBA = 		5.50824 us
Cholesky = 	2.40469 us
Jacobian = 	3.68493 us
COM+Jcom = 	4.024 us