Update OOjs UI to v0.1.0-pre (43f379c884)

New changes:
0473209 Standardize less imports and image rule generation
4ead033 Localisation updates from https://translatewiki.net.
596d4e9 Tweak behaviour to match description in demos
8846b27 Fix typo in documentation: "nodes" (pl.) goes wo. article
611703c Fix label text in RTL demo listing containing parentheses
93c4b43 Divide CSS properties between base styles and themes
6ede2d8 Reorganize theme system
3515f5a Build with clean CSS
a24c7af Make OO.ui.Window's $content a div again
ea0172d Followup 6ede2d8: fix popup font size
d72addb Fix remaining references to 'agora' not 'minerva'
f6468b8 build: Don't copy anything other than SVG and PNG files to /dist
43f379c build: Also whitelist GIF files in the copy task

Local changes:
The "Agora" OOUI theme has been renamed to "Minerva", so correct loader.
The RTL CSS files were here by mistake, and have been removed.

Change-Id: I76e47b0b53bc5652146dd24fc403591bcc54e18b