another round of my improvements

[vfosnar]

• fix floodfill timeout - didn't test this
• better wall and roof color using color distance
• pitch surface
• enable lto #67

[louis-e]

Hi there! Thanks a lot for your effort, that's amazing! I'm very busy today and the next few days with work, I'll review this asap when I'm free. :)

[vfosnar]

No worries, I'm using my own repo anyway. Just wanted to contribute my changes back ;)

[louis-e]

Looks good to me. Thank you very much for your contribution and patience! :)