Update git submodules
- Update extensions/Math from branch 'REL1_39' to ece145041a5ff541f54719758db682667788f700
- Localisation updates from https://translatewiki.net.
Change-Id: I408dbab852a89064e35535b76d5aeb5d33358c9a
- Localisation updates from https://translatewiki.net.