Handle 'unsaved' rendering setting in DataBrowser and TreeViewer
Added sanity check to CopyRndSettings event; + some code clean up
Do not save the reference image's modified renderering settings
Fixed: Paste unsaved rendering settings into full viewer
Fixed another copy/paste bug
Fixed: Save button in fullviewer now enabled if settings were modified
Removed some previoulsy accidentely commited unused code
Fixed a problem with renderer reset if it wasn't initialized before
Reload 'viewedBy' items after 'save to all'
Fixed issue with warning dialog popup
Removed some unused code
Merge pull request #3164 from dominikl/paste_pending_rendering_settings_3

Bugfixes: Copy/Paste rendering settings