butch-print: cleaning up /pkg

Just in time for butch's new [deps.host] and [deps.run], I've added a new pretty-printer to butch so that we can try and standardize what a butch package should resemble. 

'butch print (package)' will do the following: 
1. Print [mirrors],
2. [main],
3. [deps], [deps.host] and [deps.run] stripped of empty lines and sorted, 
4. while printing [build] untouched.
5. Add a newline for each sorted section.
6. Any empty section encountered will be stripped. 

The rest of the 512 commits went a little something like:

	for i in /src/pkg/*; do
		pkg=`basename $i`
		butch print $pkg > $tmp/$pkg
		if ! diff -q $orig/$pkg $tmp/$pkg; then
			cp $tmp/$pkg $orig/$pkg
			git add $orig/$pkg
			git commit -m "$pkg: formatted with butch-print"
		fi
	done