Resolve "Update i18 files"

Please make sure your MR is ready to be merged !

• You added the changes in CHANGELOG.md
• You described the MR as below

Fixes #41 (closed)

Changes :

• update po files
• Added Latvian support
• Added Luxembourgish support

Related to :

• https://gitlab.com/recalbox/recalbox-buildroot-prime/merge_requests/33