Add PerPageLicense extension.

See https://www.mediawiki.org/wiki/Extension:PerPageLicense
The PerPageLicense extension enables license footer variables
(viz. $wgRightsIcon, $wgRightsUrl, and $wgRightsText) to be
set on a per-namespace or per-page basis.

Change-Id: I9a211eea021b61c7768e2fcd0bbd6bc0111c9af8
Indent PHP file with tabs

Change-Id: I08767939e3e1d0c69c2bb5372b64fd807a10f754
Some more i18n file tweaks.

Change-Id: I067c3b17b2af7a169a13e5e393eedf7f440f807b
Pretty hard to spot a typo in a filename

Change-Id: Iad21b507396e6189b6865201e6eeb3fc51d1ceb9
Localisation updates from https://translatewiki.net.

Change-Id: Ie6620b4ef81cf63fbace029e4d614d70fe3cfac7
Localisation updates from https://translatewiki.net.

Change-Id: Id0a30a51719a4e9e0792cac740fcabeca6c47200
Localisation updates from https://translatewiki.net.

Change-Id: I2e63d36c28c0da575a339b6660289cd804507787
Migrate to JSON i18n

Procedure per https://www.mediawiki.org/wiki/Manual:GenerateJsonI18n.php
with shim.

Change-Id: I7fe694122c1a078090597dbd5a53331ef1fd507c
Localisation updates from https://translatewiki.net.

Change-Id: I8340247d9045feed072b4ad7d5ef9a117f73c755
Localisation updates from https://translatewiki.net.

Change-Id: Id8397504bd3843fa0b2ed057c056da217b34578b
Localisation updates from https://translatewiki.net.

Change-Id: Id95a60cb871814def6e127418ad187c6b9f9a558