Introduced some infrastructure for the revised prover

term_table_new: A new termtable which stores with all variables the
                number of arguments of the term and the number of
                variables above the arguments of the local environment

prover2:        Basically a proof table which can store all assertions
                with their proofs and can verify proofs. The proof table
                can work with arbitrarily stacked environments.

	new file:   ocaml/prover2.ml
	modified:   ocaml/term_table.ml
	new file:   ocaml/term_table_new.ml
	new file:   ocaml/term_table_new.mli