PlaceHolder Feature in TCEforms only works on first relation level
By separating with more | | | (pipes) relations over several levels need to be resolved.
[FEATURE] Make getPlaceholderValue recursive for __row
If __row|uid_foreign|field is a reference its not evaluated
recursive the placeholder shows a uid. With this patch the
content of the field is shown.
Additonally the type of the metadata field of sys_file was changed
to inline because select does not support the foreign_field property.