The boilerplate code for drawing the 4 types of stepped is in place (as
described in ODF1.3,
https://tools.oasis-open.org/issues/browse/OFFICE-3662).
We can also read the current attribute values used in Gnumeric. These values
are converted to ODF1.3 during save.

Change-Id: I0f04a779de4b65326ed7ce6de56191f11b51c596