Tweak the way cvars are displayed, fixes VM cvars showing empty
Fix dynamic new style Cvars not registering properly
Fix SIGFPE crash on func_door_model with speed property set
Fix eccf4722d9 (Cvar vtable problem)

The cvars would call virtual functions in the constructor which on some
compilers would cause segfaults (gcc). Move that call in the
registration of the cvar, which already has a workaround for that
problem.