UDP Fixes

-=-=-=-=-

Curse the day I decided to port UDP code, as it ended up
being two nights of work.  At least It's done now (I hope).

-Fixed UDP Support, API seems stable
-Added UDP Chat demo (chat that can lose your packets, heh)
-Added helpers to areas and bodies to get list of collided bodies and contained bodies.
-Sped up screen/viewport capture code.
-Added code to save an image as PNG
-Small fix so scripts register their singletons after modules did.

core/image.cpp

@@ -34,6 +34,7 @@
 #include "print_string.h"
 #include <stdio.h>
 
+SavePNGFunc Image::save_png_func = NULL;
 
 void Image::_put_pixel(int p_x,int p_y, const BColor& p_color, unsigned char *p_data) {
 
@@ -1200,6 +1201,14 @@ Error Image::load(const String& p_path) {
 	return ImageLoader::load_image(p_path, this);
 }
 
+Error Image::save_png(const String& p_path) {
+
+	if (save_png_func == NULL)
+		return ERR_UNAVAILABLE;
+
+	return save_png_func(p_path, *this);
+};
+
 bool Image::operator==(const Image& p_image) const {
 
 	if (data.size() == 0 && p_image.data.size() == 0)