Generic resolving: Also add generic parameters from resolved GenericInstanceMethod.
Constrained opcode: Constrained class should be cleared even if method is not actually virtual.
Readonly opcode: added empty implementation (probably fine for now since we don't do additional type checks).
Ceq/Cgt/Clt opcodes: improve error message if comparison was not possible.
Arglist opcode: Added dummy implementation (will need framework and codegen implementation).