Solving spec problems

[dachafra]

• add base IRI (add rml:baseIRI property to spec #30) done in c06e794
• clarify default base IRI (Specify default base IRI #232) done in a21adb3
• add rml:URI (add rml:URI to ontology, shapes and spec #50) b93ef2c
• Blank Nodes are allowed without reference data (clarify in the spec that BN are allowed without reference to data #52) already solved
• add rml:UnsafeIRI and rml:UnsafeURI (add rml:UnsafeIRI and rml:UnsafeURI to ontology, shapes and spec #72) b93ef2c
• OM/SM/GM no data reference (Blank Node as default termtype if nothing is provided? #111) To be Discussed in the WG
• (Should DatatypeMap be defined as a TermMap? #120) 0e363ea
• (Definition of language- and data-type maps. #145) 3361382
• (Definition of child logical source and parent logical source #212) b555621

[dachafra]

This is ready for review @pmaria