Merge pull request #174 from AdrienChampion/invGen

Inv gen
Map and guards to instantiate vars in called nodes
Merge pull request #176 from chsticksel/inv-gen

Map and guards to instantiate vars in called nodes
Merge remote-tracking branch 'upstream/inv-gen' into invGen-no-explicit
Refer to calling node in instantiation map
Remove redundant debug output
Merge pull request #180 from chsticksel/inv-gen

Refer to calling node in instantiation map
Integrating guarding in term instantiation
Merge remote-tracking branch 'upstream/inv-gen' into invGen-no-explicit
Buggy commit, two-state invgen unsound (one-state might be also).