latest changes

[Dirk Hohndel]

I didn't want to leave all the fun of breaking the code to Tomaz, so I
decided to get in on it as well. While he is off breaking the picture
handling, I decided to break^H^H^H^H^Hrewrite the dive editing code.

I think the new code is much more straight forwardward and much easier to
get right, but I wouldn't be surprised if I broke something in the
process. So please test multi (and single) dive editing with the latest
master.

For the Windows-only testers, there's a new binary at

http://subsurface.hohndel.org/downloads/outbox/subsurface-4.1-242-gb249370ffec7.exe

Thanks

/D