Add the concept of commands to the world and executing them

pkg/game/geom.go

@@ -1,6 +1,15 @@
 package game
 
-type Position struct {
-	X int `json:"x"`
-	Y int `json:"y"`
+// Vector desribes a 3D vector
+type Vector struct {
+	X float64 `json:"x"`
+	Y float64 `json:"y"`
+	Z float64 `json:"z"`
+}
+
+// Add adds one vector to another
+func (v *Vector) Add(v2 Vector) {
+	v.X += v2.X
+	v.Y += v2.Y
+	v.Z += v2.Z
 }