Simplify translation for mutually-recursive declarations.
Simplify translation for mutually-recursive declarations.

The translator now avoids the use of `instantiateVarList`, which
required an additional traversal of the produced term, and also
had error-prone conventions for de Bruijn indices.

The new version now translates declaration right-hand-sides in an
environment that maps bound names directly to the appropriate record
projections.

GaloisInc/saw-script,GaloisInc/saw-script,GaloisInc/saw-script,GaloisInc/saw-script,GaloisInc/saw-script