Distinguish between entered and calculated waypoints

Signed-off-by: Robert C. Helling <helling@atdotde.de>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Diveplan with entered and computed waypoints to UI

Recently Robert Helling provided a patch "Distinguish between entered and
calculated waypoints" in an attempt to distinguish between entered and
calculated stops.

This patch is an independent (content wise) extension of the above
patch and is built relative to it which adds new table to display
computed waypoints in plan mode.

Currently table includes only two columns "Comp. Depth" and "Comp.
Duration", which can extended to show further information.

This is only a start to the UI interaction in PLAN mode.
In addition to this there are many TODO things that diveplan feature
demands

TODO:
1. Show more details through "Computed Waypoints" table.
2. Remove tooltip from "Computed Waypoints" table widget.
3. Make contents in "Computed Waypoints" table widget non-editable.
4. Fix error when trying to save dive plan without using cylinder data.
5. Make dive plan editable after saving it.
6. Improvise dive planner graphics window.

Signed-off-by: Lakshman Anumolu <acrlakshman@gmail.com>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Merge branch 'planner-mods'

Nothing exciting here, just a few independent changes close to each other.

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