Make some dialogs modal to MainWindow

For most dialogs it would be much safer to make them Qt::WindowModal to
the parent (MainWindow).
For now we are not doing this for the preferences dialog as there are
situations where the user might want to be able to move it around and even
interact with the main window.

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

Only the change to subsurface.pro is authored by me.
The rest is generated (subsurface_source.ts) or created by the translators
on Transifex.

This adds Greek, Hungarian (partial), Latvian (partial), Romanian, and
Turkish (partial) translations.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Ruler: change how the ruler text drawing works

A couple of problems with the ruler:
- the rotated text doesn't look very well at all and interpolation doesn't
  help it much
- measuring towards the right most part of the profile makes the text go
  out of the screen

To solve these issues and attempt to improve the ruler this patch does the
following:
- place the text at the bottom of the lowest of the start and end points.
  this way the line will never intersect with the text
- clamp the x position, so that the text doesn't ever leave the screen
  horizontally
- place a white background behind the text so that it will cover text and
  graphics under the ruler item

(TODO: place the ruler on top of everything else)

Signed-off-by: Lubomir I. Ivanov <neolit123@gmail.com>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Profile2: place the ruler and tooltip on top (Z order)

The topmost Z order of items in the profile should be:
- background (poster / logo)
- toolTipItem
- rulerItem
...

This mostly fixes the ruler being under other elements.

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