[doc] Move code documentation in user/ so document link work properly

Adjust various document reference in the python docstring
[CMakeLists.txt] Provide fake env for hla, pymoos, and yarp
[ros][test] remove the 'morsetesting' ROS node

Not used anymore.
[test][pr2][ros] Added a test for PR2 arms

This test, based on the ROS 'pr2_tuck_arm' app, checks that we can control PR2 armatures, and get
an accurate feedback (via {l|r}_arm_controller/state)
[pocolibs] Don't launch an exception when CDLL in doc mode

while here, add a better error message when the library cannot be
	loaded.
[pocolibs] Rework a bit niut to help the documentation generator

- No functional changes expected
[CMakeLists.txt] Fakeenv for pocolibs for doc generation