major clean up and rework of minimap generator. it is now much faster and never skips to load an asset. it should not stall the process either.

UX improvements for dock widgets and minimap selector widget. The long requested ADT coord promt is now back.

src/noggit/map_index.cpp

@@ -1163,6 +1163,25 @@ void MapIndex::removeTile(const tile_index &tile)
   changed = true;
 }
 
+unsigned MapIndex::getNumExistingTiles()
+{
+  if (_n_existing_tiles >= 0)
+    return _n_existing_tiles;
+
+  _n_existing_tiles = 0;
+  for (int i = 0; i < 4096; ++i)
+  {
+    tile_index index(i / 64, i % 64);
+
+    if (hasTile(index))
+    {
+      _n_existing_tiles++;
+    }
+  }
+
+  return _n_existing_tiles;
+}
+
 void MapIndex::set_basename(const std::string &pBasename)
 {
   basename = pBasename;