Update git submodules
- Update extensions/VisualEditor from branch 'REL1_39' to 6eb4dc0812ddc2fe7333e23d8ae2362263c59ad2
- Localisation updates from https://translatewiki.net.
Change-Id: Ic9f007c52abb4a0aa71fc2fef59eff7507936b35
- Localisation updates from https://translatewiki.net.