Bugfix and changelog
OpenWithDlg AppList Remove from list implemented
OpenWithDlg AppList specify (and underline) preferred app
bugfixes, TODO
Bugfix with -1 preferred apps
OpenWithDlg AppList Remove improvments

1. Set preferred (and Underline) and selection to sysdefault in case
user deletes its preferred app.
2. Clear selection in other cases
[Prevent Un-associating the preferred item in the UI]
Change Cancel button to Close

Because we can make modifications in the OpenWithDialog and then Close
it. Cancel is not a good name.
Validation in BookmarkEditDialog

Just don't allow empty bookmark names
Small code improvement

by elimination of consecutive query.record()'s.
FileViewManager::PreviewStandalone convenience function
BookmarkEditDialog preview implemented.