Arch: removes unused imports

Removes unused imports as reported by LGTM.

There are exceptions: `import Arch_rc` is shown as an alert, but has side effects.  It's not clear what the best thing to do in those cases is, so I've left them for now.

src/Mod/Arch/ArchBuildingPart.py

@@ -30,7 +30,6 @@ import tempfile
 import os
 if FreeCAD.GuiUp:
     import FreeCADGui
-    from PySide import QtCore, QtGui
     from DraftTools import translate
     from PySide.QtCore import QT_TRANSLATE_NOOP
 else: