Analyzer: Re-design the diagnostics view.
The old one had a number of problems, mainly due to the awkward delegate that was used for presenting the data. For instance: - Only one diagnostic at a time could be looked at in detail. - Once it had been opened, it was not possible to close such a detailed view again, other than by opening a new one. We now use a tree view for showing the diagnostics, so users can show and hide details about as many diagnostics as they wish. That also gets us sensible item selection capabilities, so features like suppressing several diagnostics at once can be implemented in the future. Change-Id: I840fdbfeca4d936ce600c8f6dde58b2ab93b0d00 Reviewed-by: Nikolai Kosjar <email@example.com>