Adapt Y. Bertot's path on private inductives (now the keyword is "Private").

A quick and dirty approach to private inductive types
Types for which computable functions are provided, but pattern-matching is disallowed.
This kind of type can be used to simulate simple forms of higher inductive types, with
convertibility for applications of the inductive principle to 0-constructors

Conflicts:
	intf/vernacexpr.mli
	kernel/declarations.ml
	kernel/declarations.mli
	kernel/entries.mli
	kernel/indtypes.ml
	library/declare.ml
	parsing/g_vernac.ml4
	plugins/funind/glob_term_to_relation.ml
	pretyping/indrec.ml
	pretyping/tacred.mli
	printing/ppvernac.ml
	toplevel/vernacentries.ml