If you show a modal dialog while a modal dialog was already showing, the modal-backdrop could be duplicated, after which it would never be removed.  This has been fixed.
Fixed a pair of bugs where, if you reloaded a modal dialog or dismissed a modal dialog at the wrong time, then the dialog might not be fully gone.  This resulted in layering the modal-backdrop or making the modal unreachable.
Only close a modal dialog while navigating is we aren't navigating to a dialog, otherwise we sometimes can't get to the new modal dialog.  When closing a modal dialog on navigation, make sure it is open first by using an internal backbone value, as the use of a DOM class is not certain.  Don't show login or register dialogs if a user is already logged in.
Don't save login or register in the history.
Fixed many dialog navigation issues.  Specifically, folder, group, and user level dialogs are added to navigation history, used, and removed from navigation history.  Groups now use create for creation rather than edit.  Removed a debug statement.
Converted a few lines of duplicate code to a function.
Merge pull request #428 from girder/dialog-routing

Dialog routing