uobject: Throw instead of asserting in case of invalid UVar creation.
uobject: Throw instead of asserting in case of invalid UVar creation.

	* src/kernel/uobject.cc (initialize): FRAISE instead of assertion.

urbiforge/urbi,aldebaran/urbi,urbiforge/urbi,urbiforge/urbi,aldebaran/urbi,aldebaran/urbi,urbiforge/urbi,aldebaran/urbi,urbiforge/urbi,urbiforge/urbi,aldebaran/urbi,urbiforge/urbi,aldebaran/urbi,aldebaran/urbi,aldebaran/urbi,urbiforge/urbi,urbiforge/urbi