implement frames save and open from ppi

src/rtt.cpp

@@ -93,12 +93,7 @@ bool RTT::resize(int width, int height)
     
     oldRFboID = 0;
     oldDFboID = 0;
-    fboID = new_rtt.fboID;
-    rboID = new_rtt.rboID;
-    texID = new_rtt.texID;
-    int_fmt = new_rtt.int_fmt;
-    w = new_rtt.w;
-    h = new_rtt.h;
+    *this = std::move(new_rtt);
 
     return true;
 }