Close child windows and dialogs with main window

Most child windows should be closed with the main application
window otherwise if left open and if making specific
modifictions could potentially cause a SIGSEGV.

To solve that we mark all custom windows/dialogs with
the Qt::WA_QuitOnClose attribute on instance creation.

Signed-off-by: Lubomir I. Ivanov <neolit123@gmail.com>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
A couple of dialog modality considerations

While most dialogs can be open and the main application window
can still be accessed, certain should possibly be modal
in these terms.

This patch proposes the download from webservice and DC dialogs
to lock the main application window until they are closed, with
the consideration of preventing eventual unexpected behavior
in the divelist if both dialogs are active at the same time.

To solve that QtDialog::exec() is used instead of
QtWidget::show().

Signed-off-by: Lubomir I. Ivanov <neolit123@gmail.com>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Profile: move the bounding box below plot data

In certain conditions a number such as '51' could end up being
partially hidden under the white bounding box in such a way
that the digit '1' is barely visible. Putting the bounding
box bellow all plot data solves the issue.

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