Assign languages to the credentials and the remaining und.toml words #751

Part of #747. After the particles and titles, und.toml still holds the credentials (605 on master d3730550), which already carry the right kind and need only a language, and the conjunctions, bound given names and birth markers.

The work: assign each to its language files, or to mul where it is shared on purpose. Words with no language that fits stay in und, which is allowed.

Lower priority than the particles and titles: packs need these tags less.

Done when what remains in und.toml is there on purpose, the compiled sets are unchanged and the snapshot does not move.