Add dive: only copy cylinders when necessary

If the stagingDive is just an alias for the current_dive (as it is in dive
ADD mode), there's no need to copy the cylinders; they are already there.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Planner: make sure stagingDive is reset to NULL

If we first ADD a dive and then PLAN a dive, stagingDive first was an
alias to the current_dive (for ADD) - we need to make sure that when PLAN
is started, a new dive is allocated.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Planner: add missing disclaimer

This may not be the best way to do it, but it's better than just printing
"(null)".

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Planner: always recreate staging dive

Instead of even trying to keep one around (which then could cause all
kinds of trouble) we now always delete it at the end of the planner.
So simply always recreate one when starting the planner (and make sure
that the staging dive has always been cleared out, first).

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Planner: record the new dive at the correct time

We don't want to do this when calling plan() from createTemporaryPlan() -
we only want to record the dive at the end of createPlan().

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
[GSoC] Start DownloadFromDiveComputerClass

Right now this class is an empty shell, but I will build up
on it as I go along.

Signed-off-by: Joseph W. Joshua <joejoshw@gmail.com>