Removing usage of the obsolete xulrunner

--- lucidor.sh

+++ lucidor.sh

@@ -2,13 +2,11 @@

 DIR=lucidor

-if which xulrunner; then

-    xulrunner $DIR/application.ini "$@";

-elif which firefox; then

+if which firefox 2>/dev/null ; then

     firefox -app $DIR/application.ini "$@";

-elif which iceweasel; then

+elif which iceweasel 2>/dev/null ; then

     iceweasel -app $DIR/application.ini "$@";

-elif which abrowser; then

+elif which abrowser 2>/dev/null ; then

     abrowser -app $DIR/application.ini "$@";

 else

     echo "Could not find XULRunner runtime engine."