Addding support for dateliteralexpression and reject construct

• Updated grammar, metamodel to add support for date literal expression
• Added support for reject construct

v0.1.0

First release of BOCL Interpreter

• Evaluator for BOCL (BESSER Object Constraint Language)
• Library case study including domain model, object model and OCL constraints
• Researcher case study including domain model, object model and OCL constraints