- ensure that actor defaults contain a valid virtual table and class pointer so that they can actually use virtual and class-dependent method functions. This is needed for retrieving script variables from them.
- added some helpers to set scripted member variables through the native property parser.
Unfortunately some classes, e.g. PowerMorph, MorphProjectile and the powerup contain some that cannot be handled through the 'property' definition on the script side so they need to be done from the native side.
