operators without parameters have a fixed type

src/main/java/de/tla2b/analysis/TypeChecker.java

src/main/java/de/tla2bAst/BAstCreator.java

...va/de/tla2b/prettyprintb/MiscellaneousConstructsTest.java

src/test/java/de/tla2b/prettyprintb/TupleTest.java

src/test/java/de/tla2b/typechecking/ExceptTest.java

...va/de/tla2b/typechecking/MiscellaneousConstructsTest.java

src/test/java/de/tla2b/typechecking/StructTest.java