Merge branch 'feature/modeljoin-support' into 'develop'

.gitignore

build.sbt

lib/ModelSyncProvider

project/build.properties

project/sbt-antlr4.sbt

src/main/antlr4/ModelJoin.g4

src/main/doc

...el_sync/model_join/representation/core/OCLConstraint.java

...ync/model_join/representation/grammar/JoinExpression.java

..._join/representation/grammar/KeepAggregateExpression.java

...join/representation/grammar/KeepAttributesExpression.java

...join/representation/grammar/KeepCalculatedExpression.java

...ync/model_join/representation/grammar/KeepExpression.java

..._join/representation/grammar/KeepReferenceExpression.java

...el_join/representation/grammar/KeepSubTypeExpression.java

..._join/representation/grammar/KeepSuperTypeExpression.java

...ync/model_join/representation/parser/ModelJoinParser.java

...join/representation/parser/ModelJoinParsingException.java

...presentation/parser/antlr/AntlrBackedModelJoinParser.java

...oin/representation/parser/antlr/JoinStatementVisitor.java