feat(world): add a frame hitbox data structure to process

It'll allow us to create a way to process everyframe of an animation and 
change hitbox according to the animation.

It should especially simplify the creation of battle system.

examples/gameplay/plateform/actors/player.lua

@@ -9,6 +9,8 @@ function Player:new(world, x, y, id)
 
   self.isPunching = false
   self.direction  = 1
+
+  self.punchName = ""
 end
 
 function Player:updateStart(dt)
@@ -31,18 +33,14 @@ function Player:updateStart(dt)
 
   if self.keys["A"].isDown then
     self.isPunching = true
-    if (self.direction == 1) then
+    self.punchName = self:addHitboxFromFrameData({"punch", 16, 6, 12, 12, false})
-      self:addHitbox("punch", "punch", 16, 6, 12, 12, false)
-    else
-      self:addHitbox("punch", "punch", -12, 6, 12, 12, false)
-    end
   else
     self.isPunching = false
-    self:removeHitbox("punch")
+    self:removeHitbox(self.punchName)
   end
 
   if (self.isPunching) then
-    self:checkHitboxCollisions("punch")
+    self:checkHitboxCollisions(self.punchName)
   end
 
   if self.keys["start"].isPressed then

gamecore/modules/world/actors/actor2D.lua

@@ -187,6 +187,33 @@ function Actor2D:initHitboxes(w, h)
   self.hitboxes = {}
 end
 
+function Actor2D:addHitboxFromFrameData(framedata, animationID, frameID, hitboxID)
+  local sx, sy = self:getSpriteScalling()
+  local type  = framedata[1]
+  local ox    = framedata[2]
+  local oy    = framedata[3]
+  local w     = framedata[4]
+  local h     = framedata[5]
+  local isSolid = framedata[6] or false
+  local anim  = animationID or "null"
+  local frame = frameID or 0
+  local id    = hitboxID or 0
+  if (sx < 0) then
+    ox = self.w - ox - w
+  end
+  if (sy < 0) then
+    oy = self.h - oy - h
+  end
+
+  if (type == "main") then
+    self.mainHitbox:modify(ox, oy, w, h)
+  else
+    local hitboxName = anim .. frame .. type .. id
+    self:addHitbox(hitboxName, type, ox, oy, w, h, isSolid)
+    return hitboxName
+  end
+end
+
 function Actor2D:initMainHitbox()
   self.mainHitbox = Hitbox(self, self.type, 0, 0, self.w, self.h, self.isSolid)
   self.world:registerBody(self.mainHitbox)

gamecore/modules/world/actors/baseactor.lua

@@ -236,6 +236,10 @@ function BaseActor:setSpriteScallingY(sy)
   self.sprite.sy = sy
 end
 
+function BaseActor:getSpriteScalling()
+  return self.sprite.sx, self.sprite.sy
+end
+
 function BaseActor:drawSprite(x, y, r, sx, sy, ox, oy, kx, ky)
   if (self.sprite.name ~= nil) then
     local x = x + self.sprite.ox