Avoid using '-1' to avoid confusion with now legal negative tiles.
Preventing reading of bad index on horiztonal plane.
Created _wrapTile function.
Use _wrapTile method where possible.
Previous tiles outside the collision map are legal and should be tested.
Wrap horiztonal tiles when checking for vertical collision.
Only calculate prevTileWrapped if needed.
Removed comment.
Wrap Y tiles so only legal indexes are called in collision map array.