v0.1 - Release Candidate 4

The fourth release candidate of version 0.1. The following has changed from RC3:

• Add parallelization settings to Solver interface and implementations
• Add time limit settings to Solver interface and implementations
• Implement parallel ChocoSolver search using ParallelPortfolio with stealing no-good solutions on restart
• Keep element order of checked models
• Improve toString() representation of variables
• Add ElemPrinter for printing simplified string representations of elements
• Add toFullString() to Model that also includes simplified variable and constraint expressions
• Add optimizations to Checker for short-circuit evaluation of And- and Or-expressions and simplifying double negations
• Add check() method to Model that checks the Model and returns a checked and optimized Model
• Add hasVars() and hasConstraints() methods to Model
• Improve the conversion of boolean variables to constraints in ChocoSolver implementation
• Update OR-Tools and ChocoSolver