Print: provide means for profile layouting

printlayout.cpp(h):

This patch cleans some test code and adds the function
printProfileDives() that accepts a number of dives
per rows and columns. It can technically fit any number
of dives on a page given the page size allows it. Both
landscape and portrait layouts are supported.

It now replaces the old methods:
printTwoDives()
printSixDives()

Space is reserved for data tables that will be placed
bellow profiles on a later stage.

Signed-off-by: Lubomir I. Ivanov <neolit123@gmail.com>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
plot seconds with a fixed width of 2

before: 0:50 1:0 1:10
after:  0:50 1:00 1:10

Signed-off-by: Maximilian Güntner <maximilian.guentner@gmail.com>
implemented zoom action

Signed-off-by: Maximilian Güntner <maximilian.guentner@gmail.com>
Added a ruler which can be dragged along the profile

This patch adds a ruler QGraphicsItem which can be dragged
along the profile. The ruler displays minimum, maximum and
average for depth and speed (ascent/descent rate). Also, all used
gas will be displayed.

This also adds a new attribute to struct plot_data to store the
speed (not just as velocity_t).

Signed-off-by: Maximilian Güntner <maximilian.guentner@gmail.com>
Added a toolbar to the profile

The toolbar adds two buttons to the profile.
The user can now toggle the scaling (zoomed to dive/round up to 30 mins)
and adding /removing ruler to/from the profile using this toolbar.

Signed-off-by: Maximilian Güntner <maximilian.guentner@gmail.com>
correct the placement of  pressure markers

Adding +30 (seconds) to the position works fine for long dives but
when zoomed in on short dives, 30 seconds are a lot.
This commit sets the offset to +10 px regardless of the scaling.

Signed-off-by: Maximilian Güntner <maximilian.guentner@gmail.com>
Merge branch 'toolbar-ruler-rb' of github.com:mguentner/subsurface