feat(examples): add ducking in plateforming example

Show how we can now modify in action an hitbox without glitching it

CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
+### Added
+
+- **actor2D:** Make hitbox modifiable.
+
 ### Changed
 
 - **world2D:** Use a list for bodies (hitboxes, etc) and one other for actors

examples/gameplay/plateform/actors/player.lua

@@ -15,7 +15,9 @@ function Player:updateStart(dt)
     self.ysp = -280
   end
   if self.keys["down"].isDown then
-    --self.ysp =  120
+    self.mainHitbox:modify(0, 8, 16, 16)
+  else
+    self.mainHitbox:modify(0, 0, 16, 24)
   end
   if self.keys["left"].isDown then
     self.xsp = -120