Adds the Aurora Caelus, a rare event that occurs on the station space z-levels~!
During this event a .ogg will play to all clients, and you will see the outside appear almost like a storm (this is a placeholder, I need assistance from spriters to make something like an aurora or help edit the ion-storm placeholder I'm using) no longer placeholder! - consider it a fun little break and a rare/silly event.
The event announces as soon as it fires, and assuming time dilation isn't horrible, starts 10 seconds after (5 "ticks" of the event subsystem being fired by the MC).
Current event weight (frequency) can be tweaked according to admin liking, and it's currently a MUNDANE level event. This can be changed to MODERATE or otherwise as determined by admins, or given a higher weight - during testing, stuff like PDA spam or news or etc very often went over it and it took giving it a lot of weight for it to fire - but it is supposed to be a "rare" cosmic thing, not something that happens every shift.
This also resets the commit history for one clean commit.
- Creates new advanced shield generators, designed to replace old hull and bubble shield generators.
- Upgrades the floor mounted and handheld shield diffusers.
- Makes underfloor shield diffusers actually constructable.
- Handheld diffusers orderable via uplink.
- Removes supply packs and research datums for the old generators, but leaves their code in place for maps that still use them.
- Integrates with the meteor and electrical storm events.
- Integrates with mob AI (they know how to attack it)
- Move overmap defines to _defines folder. Rename old file to turfs.dm since that is what it contains.
- Definition of overmap event objects and the overmap event handler.
- Upgrades to SSevents and SSskybox to tie in the overmap events.
- Enhancement to /datum/event itself to support affecting_z and victim ship.
- Upgrade to the five event types used on the overmap to support new vars.
- Upgrade to dust and meteor spawning code to support targeting z-levels.
