upgrade lodepng to new version. remove malloc from imageutils

src/imageutils-lodepng.cc

@@ -2,25 +2,16 @@
 #include "lodepng.h"
 #include <stdio.h>
 #include <stdlib.h>
+#include <vector>
+#include <iterator>
+#include <algorithm>
 
 bool write_png(std::ostream &output, unsigned char *pixels, int width, int height)
 {
-  //encoder.settings.zlibsettings.windowSize = 2048;
-  //LodePNG_Text_add(&encoder.infoPng.text, "Comment", "Created with LodePNG");
-  size_t dataout_size = -1;
-	bool result = false;
-  unsigned char *dataout = (unsigned char *)malloc(width*height*4);
-	if (!dataout) {
-		perror("Error allocating memory while writing png\n");
-		return result;
-	}
-  LodePNG_encode(&dataout, &dataout_size, pixels, width, height, LCT_RGBA, 8);
-	try {
-		output.write( reinterpret_cast<const char*>(dataout), dataout_size );
-		result = true;
-	} catch (const std::ios_base::failure &e) {
-    std::cerr << "Error writing to ostream:" << e.what() << "\n";
-	}
-	free( dataout );
-  return result;
+	std::vector<unsigned char> dataout;
+	unsigned err = lodepng::encode(dataout, pixels, width, height, LCT_RGBA, 8);
+	if ( err ) return false;
+	output.write( reinterpret_cast<const char *>(&dataout[0]), dataout.size());
+	if ( output.bad() ) std::cerr << "Error writing to ostream\n";
+	return output.good();
 }