Fixed "call to pure virtual method" crasher upon termination. Problem was that ~SysSystemDriver called ~csWorld which called SysSystemDriver::DecRef().  However, at the start of destruction, SysSystemDriver's vtable pointer is automatically modified to point at the superclass (this is standard destruction- time behavior).  This resulted in a call to DecRef() in a class which does not implement it (since it is only implemented in SysSystemDriver -- which vtable no longer pointed at).
Fixed "call to pure virtual method" crasher upon termination.
Problem was that ~SysSystemDriver called ~csWorld which
called SysSystemDriver::DecRef().  However, at the start
of destruction, SysSystemDriver's vtable pointer is automatically
modified to point at the superclass (this is standard destruction-
time behavior).  This resulted in a call to DecRef() in a class
which does not implement it (since it is only implemented in
SysSystemDriver -- which vtable no longer pointed at).


git-svn-id: 28d9401aa571d5108e51b194aae6f24ca5964c06@2027 8cc4aa7f-3514-0410-904f-f2cc9021211c

crystalspace/CS,crystalspace/CS,crystalspace/CS,crystalspace/CS,crystalspace/CS,crystalspace/CS,crystalspace/CS,crystalspace/CS