version 2 merged

8 subgraph plug in

…l argument 'encoding' to choose between standard and bitvector smt encoding (-encoding=2)

…r being overwritten

…-id-names

Stats files naming fixed

… for verification solver

…he-allowed-error-is-0

skip iteration if the allowed error is 0

…wn-in-the-grid-exploration

28 how to manage unknown in the grid exploration

…ctoring-and-standardization

Arguments/specs refactoring and standardization

…the final layer, to avoid redundancy

* #71: arguments and usage fixes

* #71: updated required arguments and added examples to README