wip: Import module from STIX2
wip: Import module from STIX2

Functional but improvements still needed.
Not all the fields of Stix2 events supported

FloatingGhost/MISP,FloatingGhost/MISP,FloatingGhost/MISP,MISP/MISP,MISP/MISP,Rafiot/MISP,SteveClement/MISP,TheDr1ver/MISP,SteveClement/MISP,FIRSTdotorg/MISP,TheDr1ver/MISP,devnull-/MISP,SteveClement/MISP,Rafiot/MISP,TheDr1ver/MISP,Rafiot/MISP,devnull-/MISP,Rafiot/MISP,SteveClement/MISP,MISP/MISP,FIRSTdotorg/MISP,devnull-/MISP,FIRSTdotorg/MISP,MISP/MISP,MISP/MISP,TheDr1ver/MISP,FIRSTdotorg/MISP,devnull-/MISP,FloatingGhost/MISP,SteveClement/MISP