cromFFBlankGenerator causes many wasted tiles in the CROM

[city41]

The eyecatcher needs the tile at 0xff to be blank. This is done by adding cromFFBlankGenerator to the generators in cromOrchestrate. Which is fine and correct.

But later on in CROM positioning, Math.max is used to find the last already positioned tile, and then the rest of the tiles are dumped from there. That causes these tiles to get dumped at 256 on, and leaves a big gap in the CROM