Inserted all not implemented branches in the typer explicitly

	modified:   ocaml/support.ml
	modified:   ocaml/typer.ml
Added implicit result type to signatures

For quantified expressions, predicates and assertions the implicit
result type of the inner expression is BOOLEAN. For function
expressions when no explicit result type is given the implicit result
type is a fresh type variable.

	modified:   ocaml/ast.ml
	modified:   ocaml/class_table.ml
	modified:   ocaml/class_table.mli
	modified:   ocaml/context.ml
	modified:   ocaml/context.mli
	modified:   ocaml/module_table.ml
	modified:   ocaml/module_table.mli
	modified:   ocaml/parser.mly
	modified:   ocaml/proof_table.ml
	modified:   ocaml/support.ml
	modified:   ocaml/term_builder.ml
	modified:   ocaml/term_builder.mli
	modified:   ocaml/tvars.ml
	modified:   ocaml/tvars.mli
	modified:   ocaml/typer.ml
Improved error message for ambiguous expressions (more than one type)

	modified:   ocaml/feature_table.ml
	modified:   ocaml/term.ml
	modified:   ocaml/typer.ml