Merge branch 'quit-handling' of git://github.com/dirkhh/subsurface
* 'quit-handling' of git://github.com/dirkhh/subsurface:
Use the last (or only) filename on command line as default for saving
Show the "save changes" dialog before the main window is destroyed
Check for changes at regular 'quit' events as well
Catch changes to the info of the current dive when quitting
Tracking changes to tanks is trivial
Simplistic first attempt to get changes saved when quitting subsurface