Add cleanup command

* `brew cleanup foo` removes any unlinked foo kegs
* `brew cleanup` removes all unlinked kegs

Library/Homebrew/brew.h.rb

@@ -245,6 +245,22 @@ rescue
   []
 end
 
+def cleanup name
+  require 'formula'
+
+  f = Formula.factory name
+
+  if f.prefix.parent.directory?
+    kids = f.prefix.parent.children
+    kids.each do |keg|
+      next if f.prefix == keg
+      print "Uninstalling #{keg}..."
+      FileUtils.rm_rf keg
+      puts
+    end
+  end
+end
+
 def clean f
   Cleaner.new f
  

bin/brew

@@ -207,6 +207,16 @@ begin
         ARGV.named.each {|name| info name}
       end
 
+  when 'cleanup'
+    if ARGV.named.empty?
+      require 'formula'
+      `ls #{HOMEBREW_CELLAR}`.each do |name|
+        cleanup name.strip
+      end
+    else
+      ARGV.named.each { |name| cleanup name}
+    end
+
   when 'install'
     check_for_blacklisted_formula(ARGV.named)