Interior Update Beta - last one, I totally swear! — Rodina Steam update #616724

OK, I know this one has dragged on, but this should be the last beta! I couldn't help adding a few more features and cleaning up a bunch more bugs: * Added test stairs (just physics + simple boxes) * Custom light editor * Floors can now be disabled by halves. * Changed character controller to make walking up stairs possible * Fixed construction of walls with multiple tilesets at different levels * Fix tileset painting position (don't paint floor below current floor) * Some fixes to end/corner caps in interior walls * Fixed lights in tall rooms * Fixed issue with blaster charge particles * Fixed tileset weirdness due to underlying hashing error * Fixed spontaneously exiting interior when near edge of map * Fixed fires * Fixed fire extinguisher firing behind Limnal Drive * Fixed crash with holoscreen in editor * Fixed angled door placement * Fixed crash with room connections * Fix stray do...