Add a Formulary class for managing the Formulae

These methods could be static on Formula, but splitting them out makes
it clear to formular authors that these functions don't have anything
to do with writing new formulas.

Library/Homebrew/formula.rb

@@ -33,6 +33,28 @@ class FormulaUnavailableError <RuntimeError
 end
 
 
+# The Formulary is the collection of all Formulae, of course.
+class Formulary
+  # Returns all formula names as strings, with or without aliases
+  def self.names with_aliases=false
+    everything = (HOMEBREW_REPOSITORY+'Library/Formula').children.map{|f| f.basename('.rb').to_s }
+    everything.push *Formulary.get_aliases.keys if with_aliases
+    everything.sort
+  end
+  
+  # Loads all formula classes.
+  def self.read_all
+    Formulary.names.each do |name|
+      require Formula.path(name)
+      klass_name = Formula.class_s(name)
+      klass = eval(klass_name)
+      
+      yield name, klass
+    end
+  end
+end
+
+
 # Derive and define at least @url, see Library/Formula for examples
 class Formula
   # Homebrew determines the name