Added the keys in the feature table by a function and not manually

	modified:   ocaml/class_table.ml
	modified:   ocaml/container.ml
	modified:   ocaml/context.ml
	modified:   ocaml/feature_table.ml
Added some infrastructure for class inheritance

	modified:   ocaml/class_table.ml
	modified:   ocaml/class_table.mli
	modified:   ocaml/context.ml
	modified:   ocaml/eiffelc.ml
	modified:   ocaml/parser.mly
	modified:   ocaml/support.ml
Well formedness of type terms checked

It is checked whether a type of the form C[AG1,AG2,...] is well formed
in the sense that the number of formal generics correspond to the
number of actual generics and the actual generics satisfy their
concepts.

Remark: Concept checking does not yet include inheritance checking.

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