This adds 3way merge functionality to our DifferenceEngine stack. The
code was taken from the PEAR Text_Diff3 package and adapted to work with
our implementation.

For the curious:
Here's a short Origin tree of the different versions of the Diff code to
make clear how our implementation is related to the PEAR package.

-- original code Geoffrey T. Dairiki
   `-- Adaption for the Horde project
       |-- Adaption for phpwiki
       |   `-- Adaption for MediaWiki
       |       `-- Adaption for DokuWiki
       `-- Creation of PEAR Text_Diff

TLS fix for HTTPClient

This should fix the test problems errors in #1527. When requesting a
HTTPS URI from a HTTP only proxy, the initial connection is *not* TLS
secured. The URI scheme is only relevant when directly connecting.

This also changes the (wrong) assumption that everything on port 443 is
always TLS secured. Only the URI scheme should decide that.

This is to ensure that we use SSL/TLS if a custom port is defined an no
proxy is used.

Fixes #1526

Form TagCloseElements should conform to expectations of functions inherited from Element

Reflection based method export for remote plugins

make reuse of mediamanager popup easier

add support for new Django hashing methods

obfuscate auth passwords in config. fixes #1487

Translation update (ro)

The header() method of PHP is vulnerable to HTTP Response Splitting
attacks.

This change makes sure the URL passed to send_redirect (and thus to
header()) does not contain any control characters that would be needed
to execute such an attack.

Cleaning input is recommended anyway.

Translation update (pt-br)

missed a line in my last commit

This makes it easier to create tabs with an active tab (no need for
additional markup)

Translation update (ko)

Fixes for the FR translation

A few fixes.

multicheckbox without extra string input

remoteuser - Patch for default setting and improved checking in hasAccess()

we already do it for other passwords, so it makes sense to do it here as
well.

#1477:Search heading still displayed although search disabled

use getNS() call instead of dirname()

New Python Django application default to PBKDF2 with SHA256 as a
password mechanism. This adds support for that mechanism in our
password hasher class. This will be needed in the tests for the new
PDO auth plugin.

Fixes #1480

* master:
  refactor page saving and introduce COMMON_WIKIPAGE_SAVE

This makes sure the provided callback is using alphanumerics only. I'm
not sure this is needed, but better safe than sorry.

refactor page saving and introduce COMMON_WIKIPAGE_SAVE

because we actually want it in this branch ;-)

This reverts commit 38a2174b.