remove model join stuff from this project

build.sbt

project/sbt-antlr4.sbt

src/main/antlr4/ModelJoin.g4

...el_sync/model_join/representation/core/AttributePath.java

...el_sync/model_join/representation/core/ClassResource.java

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

...del_sync/model_join/representation/core/OCLStatement.java

...ync/model_join/representation/core/RelativeAttribute.java

...del_sync/model_join/representation/core/ResourcePath.java

...nc/model_join/representation/core/TypedAttributePath.java

...l_join/representation/grammar/CompoundKeepExpression.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

...odel_join/representation/grammar/ModelJoinExpression.java