Refactor to use better interfaces and event callbacks.

gameelement/gameelement.go

@@ -0,0 +1,15 @@
+package gameelement
+
+import (
+	"mover/gamedata"
+
+	"github.com/hajimehoshi/ebiten/v2"
+)
+
+type GameElement interface {
+	SetInputs(gamedata.GameInputs)
+	Update() error
+	Draw(drawimg *ebiten.Image)
+	Initialize()
+	RegisterEvents(e gamedata.GameEvent, f func())
+}