SPARQL Update Part 1: Located Triples

[Qup42]

This is the first PR in a series of PRs that will come from #1351.

Changes:

• LocatedTriple is a triple that is to be deleted/inserted and has been assigned to a block in the index.
  • An operation to locate a batch of Triples: locateTriplesInPermutation
• LocatedTriples are an ordered set of LocatedTriples.
• LocatedTriplesPerBlock are LocatedTriples for different blocks. This data structure will later exist once per Permutation.
  • An operation to add and remove LocatedTriples: add and erase
  • An operation to update IdTable by the changes: mergeTriples