Update git submodules
- Update extensions/Math from branch 'REL1_43' to b8ca39784d8ec3ffbdb2a76f711a4ac8a8f54c9a
- Localisation updates from https://translatewiki.net.
Change-Id: I31180655654dc8f0c962be345e7e45542de77afb
- Localisation updates from https://translatewiki.net.