A named entrance / exit / attention animation for UIAnimation.play.
An enum abstract over Int (just an Int at runtime). Entrance presets settle the target
back to its resting transform; exit presets (FLY_OUT/ZOOM_OUT/FADE_OUT) leave it hidden
for the caller to remove.
FLY_IN/FLY_OUT— slide in from / out toward an edge (with a fade)ZOOM_IN/ZOOM_OUT— scale from / to nothing (with a fade)FADE_IN/FADE_OUT— opacity onlyPOP— scale in with an overshootFLIP— a 2D horizontal flip-in (OpenFL has no true 3D, so this is a scale fake)REVOLVE— spin in one turn while scaling upSHAKE— a horizontal attention shake, settling backPULSE— a single scale pulse, settling back