#6918 DomainDiagram support palette entry style

Actifsource code generator for any programming language
A group can be defined for each palette entry in the DiagramType.

6918 1 DiagramTypeGroup1

In this group, the style (folder, separator) icon and parent (if it is a hierarchical nesting of the groups) can now be defined.

6918 2 DiagramTypeGroup2

Example Folder open and closed:

6918 3 DiagramTypeGroup3