add support of nsdoc files and links to Doc

...upelec.edf.riseclipse.iec61850.nsd.edit/plugin.properties

...lipse/iec61850/nsd/provider/AbbreviationItemProvider.java

...iseclipse/iec61850/nsd/provider/AgNSdescItemProvider.java

...der/AgPresenceConditionDerivedStatisticsItemProvider.java

...ec61850/nsd/provider/AgPresenceConditionItemProvider.java

...seclipse/iec61850/nsd/provider/BasicTypeItemProvider.java

...ipse/iec61850/nsd/provider/DataAttributeItemProvider.java

...eclipse/iec61850/nsd/provider/DataObjectItemProvider.java

...edf/riseclipse/iec61850/nsd/provider/DocItemProvider.java

...se/iec61850/nsd/provider/DocumentedClassItemProvider.java

...c61850/nsd/provider/FunctionalConstraintItemProvider.java

.../edf/riseclipse/iec61850/nsd/provider/NSItemProvider.java

.../iec61850/nsd/provider/PresenceConditionItemProvider.java

...c61850/nsd/provider/ServiceDataAttributeItemProvider.java

...seclipse/iec61850/nsd/provider/ServiceNSItemProvider.java

...e/iec61850/nsd/provider/SubDataAttributeItemProvider.java

...ipse/iec61850/nsd/provider/SubDataObjectItemProvider.java

...ntralesupelec.edf.riseclipse.iec61850.nsd/model/nsd.ecore

...alesupelec.edf.riseclipse.iec61850.nsd/model/nsd.genmodel

...ralesupelec/edf/riseclipse/iec61850/nsd/Abbreviation.java