Qlabelling now able to drow lines with a defined vanishing point; cannot yet define the vanishing point; but a bug occurs when passing from simple drawing mode to vanishing point drawing if you the drawing wasnt finished with a right click
Creation of a WidgetDock for vanishing points, with 3 buttons (new vanishing point, draw vanishing line and delete vanishing point) and  a combo box to select a vanishing point; Creation of the design of the Widget buttons' icons thank to Inkscape ; WidgetDock inside QLabelling but no effects yet
Merge branch 'master' of https://github.com/oliviertournaire/QLabelling

Conflicts:
	src/QLabelling/rc/QArrangementLabelling.qrc