Adding opensmt solver @GSoC 2019

[refactormyself]

So far this is the progress made on adding opensmt solver to java-smt:

• Create a basic sample (simpler than the more elaborate existing ones) to use the java-smt library
• Create a Build Script which can automatically:
  • Clone and Build opensmt2,
  • Generate the java bindings and compile if a Jar (so we a Jar and .so)
  • Copy the Jar and .so files to appropriate folder inside the java-smt
• Fixed some of the bugs in the initial attempt,
• Create SolverContext class (not fully implemented)
• Create FormulaManager class (not fully implemented)
• Create FormulaCreator class (not fully implemented)
• Create classes for supported Formulae/Thoeries and their Managers (not fully implemented)
• Create classes for the Theorem Prover (not fully implemented)

TODO: (I will like to continue with this after GSoC)

• [ ] Fix the Java Binding build
  • [ ] Write a custom interface for OpenSMT2 which will be useful in this purpose
  • [ ] Figure out how to get an array of Models out of OpenSMT and not string
  • [ ] Write a SWIG interface for the custom interface
  • [ ] Adjust the build script if needed
• [ ] Fully implement the glue code for Formula creation
• [ ] Fully implement the glue code for proving SAT/UNSAT
• [ ] Create and Implement the Model Class
• [ ] Documentation