working on iota reductions
added computational content to eliminators (probably very buggy still)
playing with destructors in coq
how to find the eliminator for a type
small addition
modified iota reduction, it remains broken
added missing util.ml file (contains a zip function only)
some example added to nat.total
rewriting normalization
made telescopes, etc, more debuggable
adding some utilities
reimplementing iota reductions (still ugly)