add nodep option to prevent raw content from being updated

raw content does not depend on the mtime of the DB
check session_id()
support mirroring
fixup the internal format of dynamic_macros
FetchPlugin: set default referrer
simplified builtin fetch_images routine.
fixup [[http://external_link http://external_image]] syntax

to support image align and FetchPlugin
TODO remove duplicated code
simple mirror action added
fixup IncludeMacro to link nonexistent page
revert &amp; to & correctly

fixup #65857 issue
PageListPlugin: fixup using getLikePages()
fixup $use_conditional_get routine and simplified
i18nize localized messages
make the GetText macro static
make etag() depends on theme,lang
TOC macro: last dot added to toc numbers like as the DocBook
FetchPlugin: urlencode some urls to fetch correctly
fixup alias using Cache class
make the alias feature more scalable

 * fixed page names with spaces
 * remove duplicated codes.
do not touch fetched text files