TreeMap - multi-language enablement

... use translated Metadata terms for Tree Dimensions (via Special
Fields)
... store the Metadaten information in Home-Layout.XML in "EN/Original
Language" and convert back/forth as needed
... fixed an issue, that Rides for a Cell are not selected in case the
resp. Metadata field is empty
Merge pull request #928 from Joern-R/pull1

TreeMap - multi-language enablement
Add dummy PD estimate if none computed

.. to stop endless refreshes of the estimates !
Merge remote-tracking branch 'upstream/master'