Whitespace fixes in dive planner

I know this may seem anal retentive... but it's driving me insane.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Support imperial measurements in dive planner / add dive

This was not as hard as I assumed it would be. I may still change the
horizontal dimension to be the more logical seconds instead of minutes,
but for now this achieves the main goal.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>