Finally write the new group properties to the bib file: icon with color, description, expanded status and automatic groups

[tobiasdiez]

Serialize and parse:

• Icon (with customizable color) that is shown in the groups panel (implements a feature request in the forum).
• Description text that is shown on mouse hover (implements old feature requests 489 and 818)
• "automatic groups" that automatically create subgroups based on a certain criteria (e.g. a subgroup for every author or keyword). Implements 91, 398 and #1173.
• Expansion status #1428

While implementing these changes, I had to introduce a new "StaticGroup" label in the bib file that replaces the old "ExplicitGroup". The problem was that the old group with legacy bib references

ExplicitGroup:StaticGroup\;0\;1137631\;1233448\;1314293\;;

otherwise couldn't be distinguished from a new explicit group with icon and color:

StaticGroup:StaticGroup\;0\;expansion\;icon\;color\;description\;;

I think we really should switch to JabRef#232 at some point.

---

• Change in CHANGELOG.md described
• Tests created for changes
• Screenshots added (for bigger UI changes)
• Manually tested changed features in running JabRef
• Check documentation status (Issue created for outdated help page at help.jabref.org?)
• If you changed the localization: Did you run gradle localizationUpdate?

[Siedlerchr]

Codewise LGTM: Just one thing I don't get from your description: The old groups can be imported right? What happens when you modify one of these old (sub) groups? Does it get changed to a new group then?

Please take a look at the codacy/checkstyle failures.

[tobiasdiez]

Yes, the old line "ExplicitGroup.." in the file will automatically replaced by "StaticGroup..." when you save the bib file. Besides the minor differences outlined above they are treated completely the same (and this change is only related to parsing/serialization; in particular there is no new "StaticGroup" class).

Fixed the imports.