Enable Boolean Term conversion in datatypes
Support Boolean term conversion in datatypes.  Not yet working: parametric DTs, tuples, and records.
Fix subtype and comparability checking for record types.
allow typenodes out of node builders
variety of fixes to tuples and records with embedded Boolean terms, and to datatypes with Booleans
supporting for datatypes TT | FF
add a failing regression: parametric datatype with Booleans (a Pair type)
update NEWS, add README