Support for expressions involving method calls with more than 124 parameters

[gjarzab]

As a performance optimization MethodNode generates a hash of method argument types to determine if the node has already completed initialization.

Currently the hashing logic relies on a fixed set of prime numbers, to combine the hash values of each of the argument types.
Typically this is not an issue, however, in cases where params arguments are involved this can cause issues.

When the number of argument exceeds 124 an IndexOutOfRangeException is thrown.

This change makes use of the HashCode type which provides functionality for merging hash codes.

[lahma]

Thank you!