faster rect command creation

include/pd/lithium/vertex.hpp

@@ -9,6 +9,8 @@ class Vertex {
   Vertex() {}
   Vertex(const fvec2& pos, const fvec2& uv, u32 color)
       : pos(pos), uv(uv), color(color) {}
+  Vertex(float x, float y, float u, float v, u32 color)
+      : pos(x, y), uv(u, v), color(color) {}
   ~Vertex() {}
 
   void Reset() {