Move GD to perl6-community-modules

This takes Coke++'s changes and adds a few additional tweaks.

Author: colomon

META.list

@@ -178,7 +178,7 @@ https://raw2.github.com/dginev/perl6-Lingua-EN-Sentence/master/META.info
 https://raw2.github.com/Heather/ignore/master/META.info
 https://raw2.github.com/labster/p6-IO-Path-More/master/META.info
 https://raw2.github.com/timo/ADT/master/META.info
-https://raw2.github.com/coke/perl6-GD/master/META.info
+https://raw2.github.com/perl6-community-modules/perl6-GD/master/META.info
 https://raw2.github.com/arnsholt/Net-ZMQ/master/META.info
 https://raw2.github.com/coke/p6-lingua-en-syllable/master/META.info
 https://raw2.github.com/tadzik/File-HomeDir/master/META.info