cp_airship_race a5

A smaller update compared to a4, this one focuses more on the rough level aesthetic and updating the 3d skybox to match the new level layout.

The map will also load and play properly without crashing retail TF2 now, so that's pretty neat. The only major difference I observed between classic and retail is the fire particles for the old balloon explosion don't play properly in retail and will need to be fixed in a future update.

Also began implementing areaportals in parts of the map to begin optimizing the overall portal flow and level performance.

After ripping up the entire map, shrinking it's overall area by 55%, and re-implementing large parts of the map's core functionality, it is now completely functional again from a raw gameplay perspective. Aesthetically the map is a lot rougher than A3, and the lighting has been set to fullbright for this release until proper lighting can get added throughout the map.

The Major Changes:

- The airships are now a lot larger, and players spawn on them.
- Every point except CP3 saw major reworks
- The layout is much smaller, and the airship top speed is much lower to compensate, this is intended to reduce the effects of lag mitigation
- There's now a song that plays at the start of the round

balloon_race_deluxe was starting to get a little unwieldy as a title so it has been renamed to cp_airship_race