World builder now loads the tile map json and usese the keys to figure out how to randomize the floor configurations.

tilemap.cpp

@@ -53,11 +53,14 @@ void TileMap::load(matrix::Matrix &walls) {
   }
 }
 
-
 const TileCell &TileMap::at(size_t x, size_t y) {
   return $display[y][x];
 }
 
+std::vector<std::string> TileMap::tile_names() {
+  return $config.keys();
+}
+
 bool TileMap::INVARIANT() {
   dbc::check(matrix::height($tile_ids) == $height, "$tile_ids has wrong height");
   dbc::check(matrix::width($tile_ids) == $width, "$tile_ids has wrong width");