add script to generate a marshalled cache

.gitignore

@@ -7,3 +7,4 @@ pkg
 publish
 coverage
 Gemfile.lock
+lib/mime/types.marshal-data

script/build_marshal_cache.rb

@@ -0,0 +1,15 @@
+#!/usr/bin/env ruby
+
+Dir.chdir(File.expand_path("../..", __FILE__))
+$: << "#{Dir.pwd}/lib"
+require "mime/types"
+
+# force mime-types to load data before we dump its internals
+MIME::Types["text/plain"]
+
+types = MIME::Types.instance_variable_get(:@__types__)
+
+file = "lib/mime/types.marshal-data"
+data = Marshal.dump(types)
+bytes = File.write(file, data)
+puts "Wrote #{bytes} bytes to #{file}"