Make MySQLi work with non-standard socket

MySQLi needs to specify the socket location as a parameter, and not as part
of the hostname.

Split the socket out of the hostname if it contains *one* colon (IPv6 safe)
after checking for the port number.

Conflicts:
	includes/db/DatabaseMysqli.php

Bug: 65998
Change-Id: I66ee34e1029bc1630669bde4272d0eae9d3fd9f1
GlobalVarConfig shouldn't throw exceptions for null-valued config settings

Use array_key_exists rather than isset to test $GLOBALS.

Bug: 66986
Change-Id: I9beabd79e1d52966b9184c9647af5a2a31c19276
(cherry picked from commit 1a059dbbe2380e9ae752daf6c5583333b5bd5f07)
SECURITY: Enhance CSS filtering in SVG files

* Filter <style> elements
* Normalize style elements and attributes before filtering
* Add checks for attributes that contain css
* Add unit tests for html5sec and reported bugs

Bug:69008
Change-Id: I732eece710f1bfaaeea1e5de541fcd4cfb375de7
Updated release notes and version number for MediaWiki 1.23.4

This is MediaWiki 1.23.4 security and maintenance release.

Change-Id: I62067c60794a002e012dc6f8c01b2a2f9fb3ed82
SECURITY: OutputPage: Remove separation of css and js module allowance

* No longer segment module origin allowance by an "only=" content
type. Both can be sensitive security-wise and there's no valid
use case for allowing CSS anywhere you want to disallow JS. Both
can significantly impact the user interface and cause unintended
actions to be taken on the user's behalf, or desired actions to
be made practically impossible.

* While at it, also remove the ability to set the module allowance
directly. The reduceAllowedModuleOrigin method is all we need.
I couldn't find usage or mention of setAllowedModules() in
mediawiki-core nor in any other Wikimedia-hosted repository.

Bug: 70672
Change-Id: I0e82755aede6ddd7101b495802a45d5fd96b6722
Updated release notes and version number for MediaWiki 1.23.5

This is MediaWiki 1.23.5 security release

Change-Id: Id27a11a4061b8b1c6c014ca86e77cc1cd028613b
Allow classes to be registered properly from installer

Because otherwise extensions can cause the installer to explode when
they can't find their own classes at entry point.

I feel dirty.

Bug: 67440
Change-Id: I235fe58125fd49319963d949faffe024684755bd
(cherry picked from commit 248ac9e9b1af986ac3238b3b5291c6d046889347)
Merge branch 'REL1_23' of https://github.com/wikimedia/mediawiki-core into REL1_23