This is the first step to allowing non-segments in the line chain.
External routines cannot be allowed to change the line chain without
going through the internal routines. To accomplish this, we remove the
Vertex() and Point() access routines and only leave the const versions.
Transformations are given for both points as well as the chain itself.
The pointer passing for display options is deprecated. This removes the
excess casting as the EDA_FRAME didn't need the base call with no value.
All requests for display options are now returned const and are updated
with a Set() routine after modification.
In Gerbview, this resolves an issue where the display options were not
stored because it was receiving the NULL from EDA_FRAME.
Seth Hillbrand
Jeff Young