[TD] add dialog to modify some dimension settings

also fix issue that tolerance could be set despite theoretically exact is true under some circumstances

also some wording improvements

also a minor fix to use 0.0 instead of DBL_MIN

src/Mod/TechDraw/Gui/QGVPage.cpp

@@ -478,6 +478,7 @@ QGIView * QGVPage::addViewDimension(TechDraw::DrawViewDimension *dim)
     ourScene->addItem(dimGroup);
 
     dimGroup->setViewPartFeature(dim);
+    dimGroup->dvDimension = dim;
 
     // Find if it belongs to a parent
     QGIView *parent = 0;