clasp version 3.3.0

New

• switched to MIT license
• added support for unsatisfiable core shrinking via option --opt-usc-shrink
• added support for core-guided optimization algorithms K and ONE
• removed dependency to Intel TBB (multithreading now only uses C++11 threads)

CLI changes:

• changed syntax of option --opt-strategy (old syntax is still supported but deprecated)
  • First argument selects the overall strategy, i.e. model- or core-guided optimization
  • Second argument selects the algorithm, e.g. K or OLL for core-guided optimization
  • Further arguments enable additional tactics, e.g. "disjoint" for disjoint core
    preprocessing in core-guided optimization
• option --pre now prints aspif by default (use --pre=smodels for smodels)
• merged option --opt-bound into --opt-mode
• merged option --counter-bump into --counter-restarts
• replaced option --opt-sat with --parse-maxsat
• merged option --dist-mode into --distribute
• merged option --del-protect into --update-lbd
• replaced numbers with named constants in various options
• added support for specifying bitmask arguments as list of named constants, e.g.
  --forget-on-step=varScores,signs,lemmaScores instead of --forget-on-step=7

Integration/clingo:

• switched to CMake for building clasp
• moved libprogram_opts to libpotassco, which is now a submodule of clasp
• added support for step-specific true var to simplify implementation of multishot propagators
• simplified ClaspFacade solving interface