add rss feed feature
merge settings.json into assets
fix site title not showing up in feed
add plugin support
fix qudian not loaded
refact markdown render handled in parser. change ejs render engine into
mustache
refact mustache template engine into jade. for inheritance convenience
remove rubbish code in render
support catlog to run in any subdirectory of project
add assets support for post
add about link in base.jade
add documentation