Update Main.cpp

OK, this runs in ~10 seconds, up from ~1 second since it now uses Complex^double powering.

But ... what the heck?! The output is not  a standard Mandelbrot set!
http://3.bp.blogspot.com/-FVHqHcsHfyk/U-J-5upHzEI/AAAAAAAABHQ/O8vaf7AaEiw/s320/M_.bmp