Fixed a nasty crash in StandUp() that occurred when the part got killed with an avatar sitting on it.
Fixed a nasty crash in StandUp() that occurred when the part got killed with an avatar sitting on it.

TomDataworks/opensim,RavenB/opensim,TomDataworks/opensim,TomDataworks/opensim,RavenB/opensim,EriHoss/OpenSim_0.8.2.0_Dev_LibLSLCC,TomDataworks/opensim,EriHoss/OpenSim_0.8.2.0_Dev_LibLSLCC,RavenB/opensim,EriHoss/OpenSim_0.8.2.0_Dev_LibLSLCC,EriHoss/OpenSim_0.8.2.0_Dev_LibLSLCC,EriHoss/OpenSim_0.8.2.0_Dev_LibLSLCC,RavenB/opensim,TomDataworks/opensim,RavenB/opensim,EriHoss/OpenSim_0.8.2.0_Dev_LibLSLCC,RavenB/opensim,TomDataworks/opensim,EriHoss/OpenSim_0.8.2.0_Dev_LibLSLCC,TomDataworks/opensim,RavenB/opensim