Hiki

* fix an arbitrary file delete vulnerabilities.
* Add Content-Length header field in downloading attached files.
* Add Vary header field.
* $SAFE=1 is set in Hikilet.
* XMLRPC is supported in Hikilet.
* fix the bug that text in a title is escaped twice.
* the amazon plugin of tDiary is imported.
* file scheme URI is converted to a link.
* use status 500 on error.
* the postable? method is added in plugins.
* enable adding a comment and changing properties with a single post in the its.rb plugin.
* session management without login is supported.
* nested inline modifier is supported.
* fix miscellaneous bugs.