Treat nullable numeric value types as numbers with respect to alignment

[jpierson]

Currently the check for numeric types isn't taking into account cases like Nullable<int> / int?. Playing around a little bit in Linqpad it looks like we should be able to do the following. I'm unsure if this would be compatible with .NET Standard 1.2 though given the differences in Reflection APIs.

typeof(Nullable<int>).IsGenericType &&
typeof(Nullable<int>).GetGenericTypeDefinition() == typeof(Nullable<>)