Allow icons to be set for objects without handlers

Simply setting an icon in QSTypeDefinitions (Info.plist) will give an object an icon now
Various improvements to handling pasteboard objects

* Give all pasteboard objects IDs
* Put the object pasteboard type in the details
* Add a few new types (RTF)
* Fix up icons for images
* Add the source app name for unknown data objects
* Avoid just naming some objects @"Text"
define an image and name for RTF text