Triple::document redundant

[niniemann]

The Triple struct contains 4 values:

• subject
• predicate
• object
  and
• document
  The latter was intended to contain information of whom this triple belongs to, but since it is stored in an RDFEntity this is redundant, and the SopranoModule e.g. discards it and sets the document-part if the triples it adds to its own model to the id of the object it is extracted from.

Since I ran into the problem that I couldn't remove a Triple because I didn't know the document-part of it, and what the SPARQL Query [1] returned was different from what was stored in the database, I think we should remove "document" from the Triple-struct.

[ctieben]

Closed in the spatial_conclusion branch.