Adds a setting to cache textile rendering (off by default).

* it uses ActionController cache store which is MemoryStore by default and can be configured with config.action_controller.cache_store
* macro processing was moved out of textile rendering so that it doesn't get cached
* no noticeable improvement is expected for small portions of text, so only texts larger than 2KB are cached

git-svn-id: svn+ssh://rubyforge.org/var/svn/redmine/trunk@3372 e93f8b46-1217-0410-a6f0-8f06a7374b81

config/settings.yml

@@ -53,6 +53,8 @@ plain_text_mail:
   default: 0
 text_formatting:
   default: textile
+cache_formatted_text:
+  default: 0
 wiki_compression:
   default: ""
 default_language: