Add an icon for Part_Export

Add the icon and make it display in the
Part workbench Part menu
Add and display Tree icon for Part_RuledSurface
RuledSurface fixes, Switch Part_Mirror to SVG icon

RuledSurface fixes,
  claim children
  correct tool tip
  change default name from "Filled_shape" to "Ruled Surface"

Part_Mirror
  Switched icon in the tool bar, menu, and tree from
  the existing PNG icon to the also existing SVG icon
flip arrow directions in Part_Export and Part_Import icons