CIF to mCRL transformer: support more CIF language features

Expressions:

• Biconditional binary expression. (!1023 (merged))
• Cast to equal type. (!1023 (merged))
• Location references. (!1023 (merged))
• Receive expressions. (!1023 (merged))
• 'If' expressions. (!1023 (merged))
• Switch expressions, by CIF to CIF transformation to 'if' expressions. (!1023 (merged))
• Binary operators div, mod (if they are compatible). (!1027 (merged))

Other language features:

• Channels, by linearization. (!1023 (merged))
• Trivially true initialization predicates in components. (!1023 (merged))
• Non-restrictive invariants. (!1023 (merged))
• If updates (#229 (closed)), by CIF to CIF transformation to 'if' expressions. (!1023 (merged))
• Equations. (!1023 (merged))