Update to soprano 2.4.1

2.4.0
* New methods Client::SparqlModel::listStatementsAsync and
  Client::SparqlModel::listContextsAsync
* Automatic query prefix expansion in NRLModel
* Automatic NRL metadata graph removal in NRLModel
* sopranocmd:
  - New paramter --nrl for sopranocmd which will trigger automatic query
    prefix expansion based on prefixes stored in the underlying model,
    automatic context creation for imported statements that do not have
    one set, and automatic metad ata graph removal on removeContext calls.
  - New parameter --graphselect which allows to convert SPARQL select query
    results into a graph result. This is very usable since SPARQL construct
    queries do not support contexts/named graphs.
  - New command 'rmgraph' which allows to delete a list of graphs/contexts.
  - New parameter --foo which enables scriptable binding results without
    variable names.
* ServerCore is now fully multithreaded allowing two clients perform
  read-only commands simultaneously.
* New Virtuoso storage backend which can either connect to a running Virtuoso
  instance or spawn one locally.
* New convenience methods to handle BackendSettings.
* New class AsyncQuery which will spawn a new thread for real asnycroneous
  query execution (in contrast to AsyncModel which only performs the actual
  query call in another thread while the iteration is syncroneous.)
* Removed redland/librdf dependancy from raptor parser.

2.3.2
* Do not fail when trying to index empty strings, but ignore them.
* Fixed parsing of plain literals with language code in sopranocmd.
* Make onto2vocabularyclass work with the redland backend (not using graph
  SPARQL queries anymore)

2.3.1
* Changed installation path of cmake modules (SopranoAppOntology.cmake)
  to <prefix/share/soprano/cmake
* Prevent the redland backend to add one statement multiple times.
* Properly handle class names containing a dash '-' in onto2vocabularyclass
* sopranocmd: Fail if trying to export a non-graph query


(markd)