PNG Stalkers v33

Changes:
- Fixed the "lean down when you look up" issue by changing display entities to vertical billboards.
- Added cleaner spawn command aliases while keeping old commands working.
- Kept the replaced non-jester PNGs from v32.

New spawn commands:
/function pngstalksafe:spawn/red_stalker
/function pngstalksafe:spawn/smile_stalker
/function pngstalksafe:spawn/golden_stalker
/function pngstalksafe:spawn/twixels_jester
/function pngstalksafe:spawn/jester_grin
/function pngstalksafe:spawn/jester_door_peek

Old commands still work too.
