qt: Language update for 0.9.3

cherry-picked from: bitcoin #e6abbce

NOTE: bitcoin_ko_KR.ts only contained translations that were
overwriting custom dogecoin-specific translations done by
@nameEO, those have been skipped.
Revert cyrillic in bitcoin_de_AT.ts
change "Bitcoin" into "Dogecoin" in *.ts after translation sync
with bitcoin/bitcoin
Merge pull request #704 from patricklodder/1.8.1-dev-lang-update

Language update from upstream