We have added a few operations to ork math objects:
* for all vec{2,3,4} and mat{2,3,4} : possibility to left multiply by a scalar (even if the scalar is not exactly of
the same type than the template of the object)
* for mat{2,3,4}: clarify between 2 operators [] for read-only (const) and [] for read-write.
* for quat:
  -> add a constructor from a rotation matrix
  -> add a function getAxis and a function getAngle.

git-svn-id: svn+ssh://scm.gforge.inria.fr/svnroot/ork/trunk@27 28599a00-4e59-401b-b2d8-d34d4661a6c9