i18n: updated translation for German
codingstyle: rename variable "hex" (conflicting with builtin)
codingstyle: replace ".has_key(...)" with "... is in ..."
codingstyle: replace comparison for equality against None with "is" expression
codingstyle: replace "not ... is ..." with "... is not ..."
codingstyle: replace "not ... in ..." with "... not in ..."
codingstyle: replace upper-case variable names with lower-case ones
codingstyle: trivial whitespace fixes