Better positioning of the plus sign icons in the Equip. tab

There are a couple of problems with said icons:
- When the Equip. tab is first seen, no relative event is monitored
so that the correct position is updated and the icons are positioned.

To solve that we connect the signal MainTab::currentChanged(int)
and call MainTab::equipmentPlusUpdate().

- When the info-profile QSplitter resizes with a snap towards/from
the edges of the main window, no resize handler is called such as
MainTab::resizeEvent().

A solution is to monitor the resize of the info-profile splitter
with MainWindow::on_infoProfileSplitter_splitterMoved() and again
call MainTab::equipmentPlusUpdate()

Signed-off-by: Lubomir I. Ivanov <neolit123@gmail.com>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Coordinate some mark_divelist_changed() calls

1) Make a call mark_divelist_changed(TRUE) when the user adds new
cylinder or weight entries.

2) Call mark_divelist_changed(FALSE) in
MainWindow::on_actionClose_triggered() so that each time after
a file is closed or a new one is created it does not ask immediately
the user for a save confirmation for the blank file/divelist.

3) Call mark_divelist_changed(TRUE) once a dive's geo location
has changed in GlobeGPS::changeDiveGeoPosition().

Signed-off-by: Lubomir I. Ivanov <neolit123@gmail.com>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Show empty labels in the Stats tab

Remove a couple of TextLabel text entries from maintab.ui
which can be seen right after program start and if no dives
are present.

Signed-off-by: Lubomir I. Ivanov <neolit123@gmail.com>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>