Improve debugging experience - implement dynamic view on PyObject #443

I watched this Dynamic C# course from pluralsight and found that implementing getdynamicmembernames gives a nice "dynamic view" option in the debugger.

Right now dynamic objects from Python to C# are black-box in the debugger.

https://www.pluralsight.com/courses/c-sharp-dynamic-fundamentals

https://msdn.microsoft.com/en-us/library/system.dynamic.dynamicobject.getdynamicmembernames(v=vs.110).aspx