Delegate.Method

This PR depends on #602. 
Here is initial implementation of #604.
As MethodInfo resolution is not super fast operation (#605), delegate includes function for its deffered resolution on first access.
Current temporary implementation of interface method MethodInfo resolution looks like hack and very slow.
Resolution of MethodInfo for interface members are not implemented yet for delegates created with CreateDelegate method and interface generic methods. (See commented lines in test DelegateMethod_Issue604.cs)