The dkim_select can start with a number, but has to contain atleast
1 letter and has to be between 1 and 63 characters long.

before the regex matched empty entries and entries starting with a number.

Some were already in English, most were still in German.

skip writing dkim-values for inactive domains
removed the public-dkim-key from the interface
added german language-file

Reverted SVN trunk back to revision 3938 to remove changes in default theme an a replacement of the ispconfig logo.

- need to have the pecl idn and intl modules installed
  or
- have the idna_convert class in the classes/idn/ path