Fix --help output with GNU fmt(1)

BSD fmt accepts two numeric parameters defining goal with and maximum
width. GNU's version, however, would interpret these numeric options as
files. Both GNU and BSD fmt(1) support the -w option to specify the
maximum width. GNU's version automatically sets the goal width based on
that value, but BSD fmt does not support setting the goal width in any
other way and does not automatically determine it either. We'll have to
live with the slightly less beautiful output on OS X and BSD, then.

Closes #5

google-font-download

@@ -51,7 +51,7 @@ url="http://fonts.googleapis.com/css"
 # Usage message
 usage() {
 	cols=$(tput cols) || cols=80
-	fmt $(( cols - 8 )) $cols >&2 <<-EOF
+	fmt -w $(( cols - 8 )) >&2 <<-EOF
 		USAGE
 		  ${0:-google-font-download} [OPTION...] [FONT...]
 
@@ -136,7 +136,7 @@ if [ $modern_getopt -eq 1 ]; then
 	fi
 else
 	cols=$(tput cols) || cols=80
-	fmt $(( cols - 8 )) $cols >&2 <<-EOF
+	fmt -w $(( cols - 8 )) >&2 <<-EOF
 		Warning: Old getopt(1) detected.
 
 		Your version of getopt(1) does not correctly deal with whitespace and does not support long options. You may