Fix a couple of clang compiler warnings:

-Wunused-variable
-Winconsistent-missing-override
-Wdelete-non-virtual-dtor
-Wunused-private-field
-Wformat

src/Mod/TechDraw/App/DrawViewPart.h

@@ -218,7 +218,6 @@ protected:
 
 private:
     bool nowUnsetting;
-    bool on1;
 /*    bool m_restoreComplete;*/
 
 };