Tweak Document Type displays

* Add "Default" column to Template->DocType
* Use Property instead of DocumentType for DataType->Property and add Property column
Show generic document type icon instead of content icon
Add Template to Template and DocType to DocType

* Unsure if these are redundant since it essentially just lists children which show in the tree anyway.  But it didn't feel right to show 0 usages for inherited types
Fix duplicate title
Add NuGet build script, fix build issues