Fixed the implementation of setVisible for group node
Merge remote-tracking branch 'origin/fix_vgl_inheritance' into vgl_testing

* origin/fix_vgl_inheritance:
  Fixed the implementation of setVisible for group node
Added first vgl test
Fixed coding style of tests
Added pick test
Merge remote-tracking branch 'origin/vgl_testing'

* origin/vgl_testing:
  Added pick test
  Fixed coding style of tests
  Added first vgl test
  Fixed the implementation of setVisible for group node