Deleted unused module Class from type.ml

	modified:   ocaml/class_table.ml
	modified:   ocaml/type.ml
Function 'split_implication' removed from 'feature_table.ml'

The function 'implication_chain' cannot yet be removed because 'Term.implication_chain'
returns the chain in a different form and 'prover.ml' still depends on the old form.

	modified:   ocaml/assertion_table.ml
	modified:   ocaml/feature_table.ml
	modified:   ocaml/feature_table.mli
	modified:   ocaml/prover.ml