Update VE core submodule to master (5a86ff9)

New changes:
6b1d082 Update OOjs UI to v0.1.0-pre (e9e435be5e)
24eec6f Fix ClickableNode documentation comment to add a missing period
d2fb10f Localisation updates from https://translatewiki.net.
5a86ff9 Update OOjs UI to v0.1.0-pre (23fb1b6144)

Change-Id: I167138e92ca502ca198692fcdd443b42d19ec1f0