Update git submodules
- Update extensions/MultimediaViewer from branch 'REL1_39' to fd4ca038192296e5c531c8e404e084fae35f868e
- Localisation updates from https://translatewiki.net.
Change-Id: I0565e93f96801e410744ade2c336ab8bd1968b72
- Localisation updates from https://translatewiki.net.