Update VE core submodule to master (3270e6c)

New changes:
959e54e Always return boolean from an action
2f37cb5 Fix demo width now that OOUI sets max height
1bfe220 Rename variables in surface#execute for clarity
5f15b95 Reduce height hack on command help dialog
15a3a46 Update inexplicably old version of PapaParse library
31cd078 Localisation updates from https://translatewiki.net.
7709239 Create ve.ui.Sequence which matches commands to typed text

Change-Id: I604902f4a9b9aa116492e840ad42c5a4a2b63157