Make :include public on I18n::Backend::Simple

Rationale: the I18n::Backend part of this library is designed to provide various modules that can be included into the I18n::Backend::Simple backend or other compatible backend implementations and thereby extend their functionality in an optional manner.

Thus, both code and documentation have been cluttered with lots of calls sending :include to the Simple backend class. It seems that we in fact treat sending include as a public API of the Simple backend class and therefor should make it public.

lib/i18n/backend/cache.rb

@@ -4,7 +4,7 @@
 # To enable caching you can simply include the Cache module to the Simple
 # backend - or whatever other backend you are using:
 #
-#   I18n::Backend::Simple.send(:include, I18n::Backend::Cache)
+#   I18n::Backend::Simple.include(I18n::Backend::Cache)
 #
 # You will also need to set a cache store implementation that you want to use:
 #

lib/i18n/backend/fallbacks.rb

@@ -6,7 +6,7 @@
 # To enable locale fallbacks you can simply include the Fallbacks module to
 # the Simple backend - or whatever other backend you are using:
 #
-#   I18n::Backend::Simple.send(:include, I18n::Backend::Fallbacks)
+#   I18n::Backend::Simple.include(I18n::Backend::Fallbacks)
 module I18n
   @@fallbacks = nil
 

lib/i18n/backend/gettext.rb

@@ -6,7 +6,7 @@
 # To use this you can simply include the module to the Simple backend - or
 # whatever other backend you are using.
 #
-#   I18n::Backend::Simple.send(:include, I18n::Backend::Gettext)
+#   I18n::Backend::Simple.include(I18n::Backend::Gettext)
 #
 # Now you should be able to include your Gettext translation (*.po) files to
 # the I18n.load_path so they're loaded to the backend and you can use them as

lib/i18n/backend/interpolation_compiler.rb

@@ -8,7 +8,7 @@
 # To enable pre-compiled interpolations you can simply include the
 # InterpolationCompiler module to the Simple backend:
 #
-#   I18n::Backend::Simple.send(:include, I18n::Backend::InterpolationCompiler)
+#   I18n::Backend::Simple.include(I18n::Backend::InterpolationCompiler)
 #
 # Note that InterpolationCompiler does not yield meaningful results and consequently
 # should not be used with Ruby 1.9 (YARV) but improves performance everywhere else

lib/i18n/backend/memoize.rb

@@ -3,7 +3,7 @@
 #
 # To enable it you can simply include the Memoize module to your backend:
 #
-#   I18n::Backend::Simple.send(:include, I18n::Backend::Memoize)
+#   I18n::Backend::Simple.include(I18n::Backend::Memoize)
 #
 # Notice that it's the responsibility of the backend to define whenever the
 # cache should be cleaned.

lib/i18n/backend/metadata.rb

@@ -12,7 +12,7 @@
 # To enable translation metadata you can simply include the Metadata module
 # into the Simple backend class - or whatever other backend you are using:
 #
-#   I18n::Backend::Simple.send(:include, I18n::Backend::Metadata)
+#   I18n::Backend::Simple.include(I18n::Backend::Metadata)
 #
 module I18n
   module Backend

lib/i18n/backend/pluralization.rb

@@ -7,7 +7,7 @@
 # Pluralization module to the Simple backend - or whatever other backend you
 # are using.
 #
-#   I18n::Backend::Simple.send(:include, I18n::Backend::Pluralization)
+#   I18n::Backend::Simple.include(I18n::Backend::Pluralization)
 #
 # You also need to make sure to provide pluralization algorithms to the
 # backend, i.e. include them to your I18n.load_path accordingly.

lib/i18n/backend/simple.rb

@@ -13,8 +13,10 @@ module Backend
     #   end
     # end
     #
-    # I18n::Backend::Simple.send(:include, I18n::Backend::Pluralization)
+    # I18n::Backend::Simple.include(I18n::Backend::Pluralization)
     class Simple
+      (class << self; self; end).class_eval { public :include }
+
       module Implementation
         include Base