gr3.surface: use gr.surface for unsupported option

gr3.surface uses gr3 to draw surfaces with OPTION_Z_SHADED_MESH and
OPTION_COLORED_MESH; for everything else it calls gr.surface.

Change-Id: Ie2e9ab655a2151306b03829e5715eca0eb61e357
Reviewed-on: https://iffwww.iff.kfa-juelich.de/review/20
Reviewed-by: Christian Felder <c.felder@fz-juelich.de>
Reviewed-by: Fabian Beule <f.beule@fz-juelich.de>
Reviewed-by: Josef Heinen <j.heinen@fz-juelich.de>
fixed documentation of gr.surface

The documentation of the option parameter now matches the enum in the
source code.

Change-Id: I89030880dbb0ac1840042c5b4c361d88855d5e4c
Reviewed-on: https://iffwww.iff.kfa-juelich.de/review/19
Reviewed-by: Fabian Beule <f.beule@fz-juelich.de>
Reviewed-by: Josef Heinen <j.heinen@fz-juelich.de>
Added some examples and documentation

Change-Id: I1bd4d96e25a3ffb4cef746496d8b333866db4dea
Reviewed-on: https://iffwww.iff.kfa-juelich.de/review/21
Reviewed-by: Josef Heinen <j.heinen@fz-juelich.de>