Improve display of variables in GetDescription

[chrisgregan]

Requested by Gyd via email.

when we call the method: public string GetDescription() { if (stringRef == null) { return stringVal; } else { return stringRef.key; } }

the result won't describe what kind of description is. also for the other XXXXData type.

my suggestion is like the code: public string GetDescription() { if (stringRef == null) { return stringVal; } else { return stringRef.key:stringRef.value; // or return stringRef.value + "(" + stringRef.key + ")"; } }