Fix Feature Branding

[cdietrich]

According to this report our Feature Branding is incomplete

https://download.eclipse.org/oomph/archive/reports/download.eclipse.org/staging/2019-12/index.html

i am not sure how to fix that.

• we dont have n branding plugins for n features
• the branding plugins contain all kind of stuff in about.ini and about.properties
• the feature provider is "Eclipse Xtext" am not sure what is used to "group" in the about dialog. (Xtend is under that point too but i guess that is ok)
• not all features are part of catgory.xmls but i am not sure how @merks scans for available features. (we have a lot of this feature contains that other or two)

[cdietrich]

see also eclipse/mwe#115

[merks]

Don't worry so much about the branding. This just means your features won't show up group in the About dialog under the associated images in that dialog.

But note that you can reuse any plugin via the plugin="x" in the element of the feature.xml; it should be some bundle that will be installed when the feature is installed.

If you have proper licenses and signatures then I'm very happy.