Added a module to each feature

	modified:   ocaml/feature_table.ml
	modified:   ocaml/module_table.mli
Added an owner class to each feature

Each feature gets an owner class which is determined from the
signature. The owner is the class with the highest module rank
which is still bound by the module rank of the feature.

	modified:   ocaml/class_table.ml
	modified:   ocaml/class_table.mli
	modified:   ocaml/feature_table.ml