CAM: Fix expression editor so that widgets refresh after closing

src/Gui/QuantitySpinBox.cpp:
- Call updateExpression() after setExpression() in QuantitySpinBox

src/Gui/SpinBox.cpp:
- Call updateExpression() after setExpression() in ExpressionSpinBox

src/Gui/Widgets.cpp:
- Call onChange() after setExpression() in ExpLineEdit

src/Mod/CAM/Path/Base/Gui/Util.py:
- Connect to showFormulaDialog signal and refresh CAM QuantitySpinBox Python wrapper when dialog closes

src/Gui/SpinBox.cpp

@@ -196,6 +196,7 @@ void ExpressionSpinBox::openFormulaDialog()
         else if (box->discardedFormula())
             setExpression(std::shared_ptr<Expression>());
 
+        updateExpression();
         box->deleteLater();
     });
     box->show();