Do not merge. Prototype for icons

Creation of prototype that loads icons from XML documentation file generated by project.

@Benglin, please review this prototype. Pay attention on CoreNodes project and classes Color and Files. Images should appear in old tooltip.
This can be simplified into one-line like this:
```cs
LibraryCustomization cust = LibraryCustomizationServices.GetForAssembly(member.Assembly);
return ((cust != null) ? cust.GetSmallIcon(member) : null);
```