towards 4.6 Beta 1

[Dirk Hohndel]

I just pushed a first attempt at ReleaseNotes out. I would love it if
people could add things that I'm forgetting. Given the 1600+ changes (with
the changes for Subsurface-mobile drowning out the ones for the desktop
version) it's a little hard to keep track ;-)

As I was playing around I noticed that

a) I can't seem to turn off dive computer reported ceiling (from the toolbar)
b) I can't seem to turn on the tissue / heat map; space is made on the
   profile for it, but nothing is drawn.

I wonder what else is broken still. So please, please keep testing, play
with all the knobs, buttons, menus, command line options, etc.

Thanks

/D