fixed and enabled generation of "coiters" theorems, including the recursive case

generate "fld_unf_corecs" as well

reactivated generation of "coiters" theorems

use map_id, not map_id', to allow better composition

open typedefs everywhere in the package

open typedef for datatypes

fixed and enabled iterator/recursor theorems

renamed for consistency

oops

tuning

for compatiblity with old datatype package: not only "recs" with "s", but also "iters" and their "fld_"/"unf_" variants

fixed bug with one-value types with phantom type arguments

imported patch debugging

repaired "nofail4" example

renamed xxxBNF to pre_xxx

fixed handling of map of "fun"

comment out code that's not ready

tuning

construct the right iterator theorem in the recursive case

some work on coiter tactic

more sugar on codatatypes

define corecursors

define coiterators

TODO

tuning

completed iter/rec proofs

TODOs

implemented "mk_iter_or_rec_tac"

generate iter/rec goals

repaired constant types