stricter audit for Emacs Lisp installs

Require that the subdirectory in site-lisp match the formula name
exactly.  This lets us provide better information in the caveats and
will make it easier for helper methods to write to the correct
location (as in in Homebrew/homebrew-emacs#13).

Library/Homebrew/caveats.rb

@@ -143,12 +143,7 @@ class Caveats
     if keg && keg.elisp_installed?
       <<-EOS.undent
         Emacs Lisp files have been installed to:
-        #{HOMEBREW_PREFIX}/share/emacs/site-lisp/
+        #{HOMEBREW_PREFIX}/share/emacs/site-lisp/#{f.name}
-
-        Add the following to your init file to have packages installed by
-        Homebrew added to your load-path:
-        (let ((default-directory "#{HOMEBREW_PREFIX}/share/emacs/site-lisp/"))
-          (normal-top-level-add-subdirs-to-load-path))
       EOS
     end
   end

Library/Homebrew/formula_cellar_checks.rb

@@ -173,19 +173,34 @@ module FormulaCellarChecks
     EOS
   end
 
-  def check_emacs_lisp(share, name)
+  def check_elisp_dirname(share, name)
     return unless (share/"emacs/site-lisp").directory?
+    # Emacs itself can do what it wants
+    return if name == "emacs"
 
+    bad_dir_name = (share/"emacs/site-lisp").children.any? do |child|
+      child.directory? && child.basename.to_s != name
+    end
+
+    return unless bad_dir_name
+    <<-EOS
+      Emacs Lisp files were installed into the wrong site-lisp subdirectory.
+      They should be installed into:
+      #{share}/emacs/site-lisp/#{name}
+    EOS
+  end
+
+  def check_elisp_root(share, name)
+    return unless (share/"emacs/site-lisp").directory?
     # Emacs itself can do what it wants
     return if name == "emacs"
 
     elisps = (share/"emacs/site-lisp").children.select { |file| %w[.el .elc].include? file.extname }
     return if elisps.empty?
-
     <<-EOS.undent
       Emacs Lisp files were linked directly to #{HOMEBREW_PREFIX}/share/emacs/site-lisp
-
+      This may cause conflicts with other packages.
-      This may cause conflicts with other packages; install to a subdirectory instead, such as
+      They should instead be installed into:
       #{share}/emacs/site-lisp/#{name}
 
       The offending files are:
@@ -206,7 +221,8 @@ module FormulaCellarChecks
     audit_check_output(check_easy_install_pth(formula.lib))
     audit_check_output(check_openssl_links)
     audit_check_output(check_python_framework_links(formula.lib))
-    audit_check_output(check_emacs_lisp(formula.share, formula.name))
+    audit_check_output(check_elisp_dirname(formula.share, formula.name))
+    audit_check_output(check_elisp_root(formula.share, formula.name))
   end
 
   private

Library/Homebrew/keg.rb

@@ -263,7 +263,7 @@ class Keg
   end
 
   def elisp_installed?
-    Dir["#{path}/share/emacs/site-lisp/**/*.el"].any?
+    (path/"share/emacs/site-lisp"/name).children.any? { |f| %w[.el .elc].include? f.extname }
   end
 
   def version