Fix typo in Vector2d documentation
Fix typo in Vector2d documentation

srbala/melonJS,rlugojr/melonJS,MarkoIvanetic/melonJS,srbala/melonJS,gopalindians/melonJS,melonjs/melonJS,melonjs/melonJS,MarkoIvanetic/melonJS,rlugojr/melonJS,rlugojr/melonJS,srbala/melonJS,TukekeSoft/melonJS,gopalindians/melonJS,TukekeSoft/melonJS,TukekeSoft/melonJS,gopalindians/melonJS,Smoss/Enoru-eco,Smoss/Enoru-eco