#948 #229 CIF to mCRL2: support more CIF concepts

• Best to review per commit. I added support for each concept in a separate commit.
• The CIF to mCRL2 transformation now supports:
  • Biconditional binary operator. Precondition checker is not updated, as precondition was missing (was a bug). In mCRL2, we use mCRL'2 == for both CIF's <=> and = now.
  • Cast expressions that don't change the type.
  • Location references. They get eliminated by linearization.
  • Channels and receive expressions. They get eliminated by linearization.
  • Trivially 'true' init preds in components. They have no effect and are thus ignored.
  • Non-restrictive invariants. They have no effect and are thus ignored.
  • 'if' expressions.
  • 'switch' expressions. Supported through conversion to if expressions.
  • Equations. Only for algebraic variables, as continuous variables are not supported. Equations get eliminated by eliminating algebraic variables. May introduce if expressions if equations are defined per location.
  • 'if' updates. Supported by transforming them to if expressions. (fixes #229 (closed))
• Other changes:
  • CifToMcrl2PreChecker: sorted the NoSpecificBinaryOp entries.

Addresses #948 (closed) Closes #229 (closed)