BFS searcher.
Renaming solver-related command-line options in order to decouple them from STP. More specifically, command-line options max-stp-time, use-forked-stp and stp-optimize-divides renamed to max-solver-time, use-forked-solver and solver-optimize-divides, respectively.

Option of running the SMT solver in a separate process (i.e. forked) set to true by default.

Options of running SMT solver forked and with optimized divides made available to Kleaver as well.
Methods getConstraintLog() and setTimeout() made virtual and moved from STPSolver to base Solver and SolverImpl classes, and consequently redefined in derived classes to call the corresponding methods down the solver chain. Method setTimeout() renamed to setCoreSolverTimeout().
TimingSolver and constructSolverChain() no longer coupled with pointers to STPSolver objects. Timeout is now set by the solver at the top of the solver chain rather than by STPSolver.
ObjectState::concreteStore initialised.
Merge branch 'master' of https://github.com/ccadar/klee
Merge branch 'master' of https://github.com/MartinNowack/klee