Fixes setting dive location via map and Save / Cancel buttons on info-panel position

[Henrik Brautaset Aronsen]

Tomaz Canabrava wrote:
> The button box on the bottom of the window made it a bit cluttered
> on small screens, this patch uses the window of the MessageWidget
> to show the butons - this way less space is used and things are better
> spaced on screen.

Very cool, Tomaz, thanks!

Is it possible to have the message widget above the scrollable area, 
like I showed in the screenshot mockup?  That way the message will never 
disappear when scrolling.

Also, I think we can shorten the text now, "This dive is being edited" 
should be enough I think.

Henrik