Update to 1.20.5

Upstream changes:
MediaWiki 1.20.5 [edit]

This is a security and maintenance release of the MediaWiki 1.20 branch.
Changes since 1.20.4 [edit]
(bug 46590) Add hook AbortChangePassword to Special:ChangePassword
(bug 47304) SECURITY: Check SVG xml encoding against whitelist
Localisation updates from http://translatewiki.net.
mwdocgen.php: Implement --version option.
Remove svnstat stuff used in Doxygen generation
(bug 43594) Correctly supress warnings that were missed after the upstream
PHP change to E_STRICT being included in E_ALL.
jshint: Allow global mw to be set in mediawiki.js

(wen)