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.
We can change the following condition so that we can decrease the indentation:

```cs
if (!ResolveResourceAssembly(member.Assembly, ref resourceAssemblyPath))
    return null;
```

Same applies to ```if (string == null) return;```.