Merge pull request #185 from AdrienChampion/invGen-no-explicit

Invariant generation, one state and two state
Improving Lustre translation

Just committing before merging develop branch
Re-use node calls with same inputs
Reduce number of state variables

- Reuse node calls
- Reuse abstractions
- Use let-bindings for inputs of node calls
Merge pull request #186 from chsticksel/inv-gen

Optimize translation to internal transition relation
Merge remote-tracking branch 'upstream/inv-gen' into invGen-no-explicit
Annotate properties with source, better slicing

Slice to cone of influence of properties in the top node, not regarding
those properties that were instantiated from subnodes.
Merge pull request #187 from chsticksel/inv-gen

Annotate properties with source, better slicing
Merge remote-tracking branch 'upstream/inv-gen' into invGen-no-explicit
Deactivated trivial invariant pruning.
Options for candidate lifting and trivial invariant pruning.