fixed horizontal offset error

Basically, the LPM instruction (3 cycles) does not always take 3 cycles,
(I think because of the timing needed to read the Flash memory),
and this disrupts the timing of the signal, leading to some offsets
depending on what is shown on the line.

Thus, the LPM instruction has been replaced with an RJMP one, which,
instead, always takes 3 perfect cycles to be performed, timing is
not disrupted anymore, and image appears ok.

frame.cpp

@@ -100,7 +100,8 @@ int main(int argc, char** argv) {
                     outfile << '\t' << "brne 1b" << std::endl;
                 }
 
-                outfile << '\t' << "lpm" << std::endl;
+                outfile << '\t' << "rjmp 2f" << std::endl;
+                outfile << "2:" << std::endl;
 
                 last = current;
                 count = 1;