Created the posAtValue method for the ruler

Created the posAtValue method for the ruler, you enter
a value, and it will return the coordinates in double
( coordinate system of a QGraphicsScene is double based )
this is not the best name for the function, but I couldn't
find any better suitable name.

Signed-off-by: Tomaz Canabrava <tcanabrava@kde.org>
Do not plot dive handlers outside of the Plane area.

This patch makes the behavior of inserting new hanflers
correct. it can only be inserted now inside of the plane
defined by the Depth ruler and Time ruler.

Signed-off-by: Tomaz Canabrava <tcanabrava@kde.org>
Makes the first and last line of the plot inside of the boundingrect

This patch makes the first line and the last line of the plot
inside of the boundingRect defined by the timeLine and depthLine

Signed-off-by: Tomaz Canabrava <tcanabrava@kde.org>
Depth doesn't suppose to show  broken numbers.

This patch makes the depth to show only integers, as
dirk asked. I'v also added a 'm' at the end, I know that
this will need to be taken from the settings  but
i feel lazy today =p

Signed-off-by: Tomaz Canabrava <tcanabrava@kde.org>
Make the plot and handle movement stick to an 'Grid'

Make the plot and the handle stick to a grid, the
grid is defined by the integers in the rulers, so
a time of 10,2 is converted to 10, and will put the
point at 10.

Signed-off-by: Tomaz Canabrava <tcanabrava@kde.org>
Added a new class to handle the pseudo-buttons on the canvas.

Added a new class, named Button, that has a clicked() signal,
and can be connected to the view to emulate buttons. While
I know that Qt supports widgets on canvas - I think it's too
nineties to have such square controls on something that can have
rounded borders.

Signed-off-by: Tomaz Canabrava <tcanabrava@kde.org>
Added the skeleton implementation of the increaseTime and depth

Added the skeleton implementation of the increaseTime and
increaseDepth methods - they will increase the time / depth by
10 units ( feets / minutes ) each time they are clicked.

Signed-off-by: Tomaz Canabrava <tcanabrava@kde.org>