performance issue when expanding checkstyle markers

[Bananeweizen]

Start an IDE which already has some checkstyle problem markers. Ensure to NOT trigger any scan, so the checkstyle modules metadata is not yet loaded. Expand the problem marker group containing the checkstyle markers (e.g. the "errors" group, or the "checkstyle issues" group, depending on how you have grouped them in the problems view).
This leads to blocking the IDE for as long as it takes to load all the metadata. This is because the problem marker images get a decoration which indicates if a marker has a quickfix. The information about quickfixes is attached to the metadata. This needs to be changed. Possible changes:

• have the quickfix itself contain the checkstyle module id that it can fix. That way loading of metadata is not necessary just for browsing the problem markers.
• have an OSGI declarative service triggered on "application started" lifecycle event (that means when Eclipse is up and running) and load the metadata concurrently at that time. This would mean loading the metadata as early as possible, therefore avoiding the delay later.