Add shortcuts to some Theorem argumentsnts (as requested in #8809)
de.po: update
sk.po update
Merge branch 'master' of git://git.lyx.org/lyx into my-two-cents

# By Juergen Spitzmueller (2) and Kornel Benko (1)
# Via Kornel Benko
* 'master' of git://git.lyx.org/lyx:
  sk.po update
  de.po: update
  Add shortcuts to some Theorem argumentsnts (as requested in #8809)