Index media usage data

HTML5isation of some forms

Add AES encryption and better random numbers FS#2685

The current message confusingly mentions bad 'username' when username is not involved.  The
new message is the same as that introduced for an incorrect current password on the self
delete profile form (FS#2751)

The refshow configuration option wasn't used as described anymore
already in the latest release and after the introduction of the media
usage index the parameter is also no longer relevant for internal
optimization. The only place where it was still used is the no longer
used search_references()-function which is removed here, too.

This adds a new parameter to ft_backlinks() to ignore permissions which
is needed for invalidating the cache of linking pages with useheading
enabled. This also adds various test cases for ft_backlinks().

Added an explanation that what we do is like normal CBC but that we
additionally encrypt the IV which is actually suggested by the NIST for
non-random (but unique) IVs. In the decryption process it's not
necessary to decrypt the IV, this should save some time.

This replaces the deprecated and broken Blowfish implementation that has
previously been used and should provide a lot more security.

adding ACL handlers to xmlrpc

The POST data contained the raw data instead of an array with the data
that should be submitted like in the requests from the browser. The
server backend has been fixed to be able to process both versions.

the _redirect function is not used in DokuWiki anyway

add newest plugin types to info plugin

Add media_isexternal