external command 'brew readall' that tries to import all brews

This can be useful for debugging when making changes to formula.rb,
since that can cause problems across all formuale.

Library/Contributions/examples/brew-readall.rb

@@ -0,0 +1,7 @@
+# `brew readall` tries to import all formulae one-by-one.
+# This can be useful for debugging issues across all formulae
+# when making significant changes to formula.rb
+
+require 'formula'
+names = []
+Formulary.read_all { |name, klass| names << name }