[Refactoring] Enable CodeIssuePad.
[Refactoring] Jump to source on double click in CodeIssuePad.
[Refactoring] Add infrastructure for issue grouping to CodeIssuePad.
[Refactoring] Some cleanups in CodeIssuePad.
[Refactoring] Add unit tests for IssueGroup and do some cleanups.
[Refactoring] Add tests for CategoryGroupingProvider.
[Refactoring] Use a set instead of a list.
[Refactoring] Make it possible to cancel a running analysis.
[Refactoring] WIP: Grouping UI + Lazy tree building.
[Refactoring] Small cleanup in GroupingProviderChainControl.
Add some documentation comments.
Make chained grouping work.
[Refactoring] More cleanups.
Fix issue tree update bug
[Refactoring] WIP: Begin move away from evented ui updates of issue tree.
[Refactoring] Add more grouping options.

Also, some general ui work.
[Refactoring] Store the runner state explicitly in CodeIssuePad.
[Refactoring] Factor out CodeAnalysisBatchRunner from CodeIssuePad.
[Refactoring] Enable CodeIssuePad.
[Refactoring] Jump to source on double click in CodeIssuePad.