Version 1527 was commited by markb on 2010-01-28 13:25:45 +0000 (Thu, 28 Jan 2010) Extend sea generation code to cope with "anti-islands". Anti-islands are closed polygons tagged with natural=coastline whose direction is such that the water is on the inside and the land on the outside. These are re-tagged natural=water so that they will be visible above the land background. If the tile contains at least one anti-island and no other coastline reaches the edge of the tile, it is assumed that the tile background should be land and not sea. Anti-islands that are surrounded by water don't make sense so they are converted into islands (they were probably meant to be islands but the points were mistakenly drawn in reverse order).