removed zip and unzip from lib.ml. Used combine and split instead.
Merge branch 'cex' of https://github.com/kind-mc/kind2

Merging Christoph's integration of variable reconstruction into kind2 so that I can debug it.
Append oracles onto formals, so that we can combine them without causing a crash.
And because we need to substitute actual oracles for formal oracles.
output streams are now substituted when descending into calls
all ancestor models are collected into a map to be used for evaluation
Merge pull request #106 from kevinclancy/master

Error/Bug Fix for Stateless Variable Reconstruction