fix #245: do not send mails to a person twice if he/she is delegate and editor.
refactor the email recipient handling
fix #295: add an option to send emails to the responsible person.
fix a code duplication and the bug that resulted from it
fix the "import_ad" script
eliminate most of landscape low issues (mostly code styling), raise strictness to medium
fix excel export colors again
eliminate a lot of landscape medium issues
small refactorings in the excel exporter