coalesce texture uploads at the beginning of a frame

src/map/map.cpp

@@ -558,6 +558,10 @@ void Map::render() {
 #if defined(DEBUG)
     std::vector<std::string> debug;
 #endif
+
+    glyphAtlas->upload();
+    spriteAtlas->upload();
+
     painter.clear();
 
     painter.resetFramebuffer();