FMod - Yet another flood fill fix

The tester for v2.9 noticed a subtle bug. The flood fill tool doesn't fill the very upper-left tile unless that is the tile selected as the start of the fill. The problem is that the flood fill routine stores the list of visited locations as numbers in XXYY format and checks that the value under consideration is greater than zero. I wrote that check to prevent negative values (outside the level bounds) from causing overflows, but it should have been a greater-than-or-equal comparison, not just greater-than. Correcting that fixed the problem. I'll probably publish v2.9 tomorrow.