Update Game.pot & translation files

[TentativeConvert]

I noticed while preparing #170 that:

• There are already a number of commits that are not reflected in Game.pot.
• The existing po-files have not been updated to the new lean-i18n format in which latex and lean snippets get replaced by placeholders. At least the msgid's in these po-files need to be updated.

Therefore, I haven't included an updated Game.pot file in #170, nor updated json files. But these updates need to happen before the current version gets deployed.

[joneugster]

I thought lean4game had a backwards compatibility built in to still accept the old translations without placeholders, so this should not be that much of an issue, no? Still, should be updated 👍

[TentativeConvert]

Indeed. You made lean4game more clever than I realized. Poedit is not as clever, though, and believes the setup is broken.

In any case, I believe the most recent changes to the English strings will be fixed in the translation files by #172.