This version includes:

* basic heimdall.connectors.rdf.createDatabase function
* support of the following formats:
  - rdf:hext
  - rdf:json-ld
  - rdf:nt
  - rdf:pretty-xml
  - rdf:trig
  - rdf:turtle

Cette version inclut:

* fonction heimdall.connectors.rdf.createDatabase basique
* export des formats suivants:
  - rdf:hext
  - rdf:json-ld
  - rdf:nt
  - rdf:pretty-xml
  - rdf:trig
  - rdf:turtle

Signed-off-by: Régis Witz <regis.witz@cnrs.fr>