Add type parameter inference

[ReedOei]

Currently, the user must write all type parameters explicitly, for both constructor calls and transaction calls. However, as in Java, this could usually be inferred:

contract A {}
contract B[X@s] { }
main contract Main {
    transaction test() {
        // This should be equivalent to the below code:
        B[A] b = new B[A](new A());
        B[A] b2 = new B[](new A()); // Java diamond-operator-style
        // or
        B[A] b2 = new B(new A()); // Scala-style
    }
}