Add OverwriteOrCreateRule
Add a variable selector to query the values of Goobi internal variables
Call data copier from export routines, add documentation
Get it to work
Fix typo in new class files and some javadoc
Add missing newline at end of file

Signed-off-by: Stefan Weil <sw@weilnetz.de>
Merge pull request #200 from matthias-ronge/issue_172

Merge:  Keep process ID during METS/MODS export (#172)
Apply metadata copier on METS-only export, too
Merge remote-tracking branch 'matthias-ronge/issue_172' into 1.10.x
Merge remote-tracking branch 'stweil/fix-eof' into 1.10.x