[Open Assets] Pipe Plaza from Mario Kart: Double Dash!! (Battle Plus support!)

Ayy, I love Pipe Plaza! This works well for Srb2k's battle mode too!

The references to different versions of the map are a nice touch, and it's a good size to cause chaos with other players. The pipes always have been a good strategic element, so glad to seem them work well here too. Battle mode might be much less played than race, but I feel like any battle server should still use this map!