graphicsmagick 1.3.18

Picking up where brxfork last left off with his original pull request, as another end-user whom has interests in getting this upstream! :) 

Compiles cleanly, with and without --with-perl, on my v10.9 dev box! I do not have perlbrew installed at the moment, so I tested the formula via hacking 'sudo' on and off 'make install' of the module to ensure correct response from homebrew.

See #12920

Cheers!