Now used instead of QgsPalLabeling for labels/diagrams
This code has been funded by Tuscany Region (Italy) - SITA (CIG: 63526840AE) and commissioned to Gis3W s.a.s.
The old behavior was to render it at the currently visibleExtent based on the
map canvas. The job may however have been scheduled for a different extent and
therefore rendered at an improper location.
When printing on Windows, the printing does not seem to work
well in the worker thread as QImages get converted to QPixmaps.
Therefore we force the map rendering into main thread to avoid the issues.
I do not have a printer, so I can't confirm the fix really helps
