add dive implementation pushed

[Dirk Hohndel]

This uses part of the planner widget to allow the user to actually
create a profile for their dive.

Right now it has some SERIOUS shortcomings.

It picks a non-timezone adjusted "current time" as start time of the
dive and does not allow editing that start time (yeah, I know, that's a
deal killer all by itself - but I need a bit of Qt help to get this
right).
It also doesn't allow the user to set air pressure, air temp and water
temp.

I'm sure it also has a few other, less obvious bugs.

But I think it's a step in the right direction.

My thanks goes, as always, to Tomaz for helping me over a few hurdles in
the process... one day I will be able to write Qt code without
constantly asking on IRC what it is that I am doing... but then again,
that's exactly how I felt with the Gtk code when I started, except there
wasn't anyone on IRC to ask for help... instead I asked others who also
had no idea how to write good Gtk code :-)

/D