added checking for same error type in different use type libraries
Fixed hazard definition (back to property definition)

Added constant labels to be used for value of severaity and criticality.
Brian had changed them to be integers.

Added ARP4761 and MILSTD882 with hazard definitions that use
enumerations.
committing so merge can work
Merge remote-tracking branch 'origin/develop' into develop

Conflicts:
	org.osate.xtext.aadl2.errormodel.ui/src-gen/org/osate/xtext/aadl2/errormodel/ui/contentassist/antlr/internal/InternalErrorModelParser.java
	org.osate.xtext.aadl2.errormodel/src-gen/org/osate/xtext/aadl2/errormodel/ErrorModel.genmodel
	org.osate.xtext.aadl2.errormodel/src-gen/org/osate/xtext/aadl2/errormodel/ErrorModel.xmi
	org.osate.xtext.aadl2.errormodel/src-gen/org/osate/xtext/aadl2/errormodel/parser/antlr/internal/InternalErrorModelParser.java
	org.osate.xtext.aadl2.errormodel/src-gen/org/osate/xtext/aadl2/errormodel/serializer/AbstractErrorModelSemanticSequencer.java
	org.osate.xtext.aadl2.errormodel/src-gen/org/osate/xtext/aadl2/errormodel/serializer/AbstractErrorModelSyntacticSequencer.java
	org.osate.xtext.aadl2.errormodel/src-gen/org/osate/xtext/aadl2/errormodel/services/ErrorModelGrammarAccess.java