Add Rotation class (using KDL Rotation as starting point) and relative tests
Add a couple tests for Rotation class
Add Frame (with related tests)

- add Frame class to represent 3D rototranslations
- integrate Frame class into iWholeBodyModel
- update icubWholeBodyModel accordingly
- add tests for Frame class in wbiTest
Update locomotionControl to use Frame class

- introduce use of the new Frame class into locomotionControl
- use Frame rather than double* as output of computeH method of
iWholeBodyModel
- add some methods to Rotation and Frame
Correction for compiling on Linux: removed unnecessary namespace specification in norm3d and used cmath in place of math.h
Remove user input request in wbi tests

Wbi tests now return EXIT_FAILURE (i.e. 1) if any test failed.