Fixed: PostMaster Filter // possibility to Set more Email Headers (bug#10320).
Squashed commit of the following:

commit ee4913ca90f0c721944ad78c1c1daa6f6aa31a41
Author: s7design <otrs@s7designcreative.com>
Date:   Tue Apr 1 10:49:21 2014 +0200

    changed and cleaned code

commit 8e5f5776bbac4633b4d41e7c531e8d783c4218fa
Author: s7design <otrs@s7designcreative.com>
Date:   Tue Apr 1 10:49:09 2014 +0200

    changed and cleaned code

commit 73e301b52ba284b7fb3d602d5cccb12e3875e191
Author: s7design <otrs@s7designcreative.com>
Date:   Thu Mar 27 16:44:34 2014 +0100

    [Bug 10320] PostMaster Filter // possibility to Set more Email Headers

    Changed logic, added config item NumberOfHederFields, cleaned code.

commit ff1ee37d205c849e94315a069beeddcb2e062165
Merge: aff6dbb a7a2d13
Author: root <root@ubuntu.(none)>
Date:   Thu Mar 27 16:32:26 2014 +0100

    Merge remote-tracking branch 'upstream/master'

commit aff6dbb28f9c815ced086fc2846c41c87b36992a
Author: s7design <otrs@s7designcreative.com>
Date:   Wed Mar 26 17:35:46 2014 +0100

    [Bug 10320] PostMaster Filter // possibility to Set more Email Headers
    Changed the logic in the .tt file to not duplicate the code for every
    field. Now, the fields are created in loop.
Removed line numbers. Improved wording in GUI.
Fixed incorrect relative time calculation for minute range.
Fixed: Fallback configuration for scheduler log is wrong (bug#10431).
Merge remote-tracking branch 'upstream/master' into otrs-master