Fix wide tiles issues in some levels

[Rémi Verschelde]

As mentioned in #12:

Also several tilemaps have issues with flipped tiles that are bigger than a 1x1 tile, due to a fix in 2.0 that this specific use case in older games. I fixed quite a few of them manually, but not all levels; we should probably assess these levels before trying to fix them all as it's really time consuming.

So we kind of need to review the levels before doing this boring job, but it will have to be done nevertheless.