Replace eight calls for warp on npc/000-2-1 by slide calls

Just wanted to say I'm still alive, although this may improve game performance.

It's still in legacy syntax (without parenthesis). It uses a feature 4144 implemented. It was not done everywhere, only on Peter and on the Magic Arpan. I'm not using slide_or_warp either (probably shouldn't be used on this cas).

Anyway and more importantly, happy new year!