Major redesign of rendering pipeline that separates pages saved with MCE from pages saved with the plaintext editor (full description in long commit message)
- Pages are now stored with an extra metadata field called page_format which is "wikitext" or "xhtml"
- New $flags parameter + RENDER_* constants added that control RenderMan::render() behavior
- Several other changes:
* Added a sprite API for Javascript and made editor use sprites when possible
* Removed a number of config options from the default install schema, replaced with second parameter to getConfig() calls
* MessageBox in editor mostly replaced with miniPrompt
* A few bugfixes related to password changes (registration didn't even work)
* Rewrote the bitfield compression algorithm used to serialize allowed MIME types
* Fixed some typos in language files and strings
* Fixed a Text_Wiki bug in Heading parser
