Update git submodules
- Update extensions/Gadgets from branch 'REL1_40' to 1b2d597cd75a3c9323af0edd314e1128a8177f84
- Localisation updates from https://translatewiki.net.
Change-Id: I7ea4eb7440d8e3c93fa20e3ec9520250a39f72ea
- Localisation updates from https://translatewiki.net.