event: remove dead code.
event: remove dead code.

This "children" stuff has never been used since its inception, back to
commit:1cdd0a1032f79ce5575d861918d0007a66b373d9.

	* src/object/event-handler.cc: Here.

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