Rewrite Map: Lock tiles against going OOB.

That solves some errors related out of bounds access.
Sometimes it happens when drawing a tile, others when checking passability.

It may differ from how maniacs deals with this (I suspect maniacs have an extra blank tile, with locked passability, just for OOB tiles).

src/spriteset_map.cpp

@@ -175,13 +175,15 @@ void Spriteset_Map::SubstituteUp(int old_id, int new_id) {
 }
 
 void Spriteset_Map::ReplaceDownAt(int x, int y, int tile_index, bool disable_autotile) {
+	if (tile_index >= BLOCK_F_INDEX) tile_index = BLOCK_F_INDEX - 1;
+
 	auto tile_id = IndexToChipId(tile_index);
 	tilemap->SetMapTileDataDownAt(x, y, tile_id, disable_autotile);
 }
 
 void Spriteset_Map::ReplaceUpAt(int x, int y, int tile_index) {
 	tile_index += BLOCK_F_INDEX;
-	if (tile_index >= NUM_UPPER_TILES + BLOCK_F_INDEX) tile_index = 0;
+	if (tile_index >= NUM_UPPER_TILES + BLOCK_F_INDEX) tile_index = BLOCK_F_INDEX;
 
 	auto tile_id = IndexToChipId(tile_index);
 	tilemap->SetMapTileDataUpAt(x, y, tile_id);