printing for Qt plot widget (bug #42537) * Backend.h, Backend.cc (Backend::print_figure): New function. * Canvas.h, Canvas.cc (Canvas::print): New function. * Figure.h, Figure.cc (Figure:print): New function. * Object.h, Object.cc (Object::slotPrint, Object::print): New functions. * ObjectProxy.h, ObjectProxy.cc (ObjectProxy::print): New function. (ObjectProxy::sendPrint): New signal. (ObjectProxy::init): Connect sendPrint signal to slotPrint slot of current object.

<!DOCTYPE RCC><RCC version="1.0">
<qresource>
  <file>images/pan.png</file>
  <file>images/rotate.png</file>
  <file>images/select.png</file>
  <file>images/zoom.png</file>
</qresource>
</RCC>