Update VE core submodule to master (b7b56dd)

New changes:
6b820e6 [BREAKING CHANGE] Unisolate dialogs
0bae8f4 Fix selection when inserting a caption
6a31afd Localisation updates from https://translatewiki.net.
ab362b4 Add sparse table demo and fix related selection bug

Change-Id: I8d95b32d01e7a8e1aa9db0e4dc7a2e1e470bd46d