Log Message:
Update cad/oce to 0.18.1.

- Added missing ErrorStatus function in BRepLib_CheckCurveOnSurface
- Install Shaders directory to resource folder
- Fix normals of generated VTK polydata
- prevent DRAWEXE from being added to OCE_LIBRARIES (issue #660)
- Fix warnings with VTK 7.1
- Fix missing include and other minor header issues
- Fix clockget_time detection on osx