Update git submodules
- Update extensions/CategoryTree from branch 'REL1_39' to 9e6b7c8d8c904b474b26c6b4d8f9b465ee07e6aa
- Localisation updates from https://translatewiki.net.
Change-Id: Ib30191e83cae4155d2b8b8c5bfedfb927bea0ceb
- Localisation updates from https://translatewiki.net.