Meteor Stuff

Removes meteorhit()

Meteor impacts call ex_act(2) instead
Meteors can penetrate things better in general
Adds new meteor types with special effects.
Meteors drop some ore, depending on the type of meteor.
Adds rare alternative meteor event.

Uses byond rotation features to make meteors spin. - Thanks Mr.Person
Refactors space dust event as a subtype of meteors. Reduces rate of space dust occurance by half. This will have a noticable effect on event rates- the event pool will be less saturated with dust, so other events will happen more often.

fixes issue #990