Improve Errormessages in webCube

Errormessages in webCube sometimes are inconsistent and miss basic information

Opening an webCube URL with ?action=showsearch&mode=0&id=XXXX:

"The search cannot be carried out because the user does not have the required access rights." --> that's not correct, the dialogue with the ID XXXX is not existing

Opening an webCube URL with ?action=showsearch&mode=1&id=XXXX:

"The search dialogue (XXXX) could either not be found or access rights are missing. Please contact your system administrator for further information" --> that's good, but it would be nice to see the name of the search dialogue and not the ID (or both).

Archiving a document without permissions on the database:

"The file could not be saved" --> in wincube we can show details here, in webcube this is all we get. We would like to know the reason why it could not be saved (in this case it is because of missing permissions.