Graphics class usage screwup

Some fp_Run* drawing functions get a DrawArgs object passed to them.
Sometimes this DrawArgs class contains a graphics object which should be
used.

Typically these functions start with code like this:

        GR_Graphics* pG = pDa->pG;
        if (pG == NULL)
        {
                pG = getGraphics();
        }

For the rest of the function, you have to use pG. However, we screw up
in a lot of places, and use getGraphics() anyway.

The attached patch fixes this (I'm not aware of any direct bug it fixes,
but it *is* wrong afaik). Any objections?

  Marc