planner changes and new strings

[Dirk Hohndel]

As these things go, that one was stupid and self inflicted.

planner.c still had a bunch of "printf-style" errors and warnings with
non-translated strings. I have no idea what I was thinking when I went
through the code to catch untranslated strings last week...

So when I fixed the issues with extremely long and deep dives (you now
get a warning on plans below 150m and we refuse plans below 400m; you
also get a warnings if you exceed 3h with the planned segments before
the ascent) I also cleaned up all the warnings and error messages there
(and added a few new ones).

The result is a much more reasonable planner experience with somewhat
useful errors and warnings, displayed in red in the planner dialog. This
has been tested with a 399m dive that took 140 hours to get out of the
water (non of the wimpy dives that you do, Jan...). Besides being
ridiculously unrealistic, the dive also took about 10 minutes to
calculate on my reasonably fast machine. So we are pushing the edges of
usefulness here.

Anyway, I think that solves the issues reported by Chris, Sergey, Robert
and others.

And it causes a bit of new work for the translators. :-(

The new strings, however, should be reasonably easy to translate, I hope:

+msgid "Can't find gas %d/%d"
+msgid "Cylinder for planning"
+msgid "Invalid depth - could not parse \"%s\""
+msgid "Invalid depth - values deeper than 400m not supported"
+msgid "Invalid gas for row %d"
+msgid "Invalid starttime"
+msgid "Too many gas mixes"
+msgid "Too many waypoints"
+msgid "Warning - planning very deep dives can take excessive amounts of time"
+msgid "Warning - extremely long dives can cause long calculation time"

Yes, I know, allowing myself 10 new strings at this stage is highly
inconsistent compared to what I said earlier. Sorry guys, but as it was
the planner was just CRAP.

/D