Improve MGM2Mind by adding a Scala representation of Offer, Move, UnilateralMove and BilateralMove
This merge request includes an improvement for MGM2Mind based on:
- an abstract class representing a move
- a class representing an unilateral move
- a class representing a coordinated bilateral move
- a class representing an offer
- some functions for comparing floating-point numbers in Scala
- the method relevantConstraints(constraints: Set[Constraint]) : Set[Constraint] of the class Variable