Fix a lot of typechecking bugs with user definitions and ints vs reals

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

src/main/java/de/tla2b/output/TlaTypePrinter.java

src/main/java/de/tla2b/output/TypeVisitorInterface.java

src/main/java/de/tla2b/types/AbstractHasFollowers.java

src/main/java/de/tla2b/types/FunctionType.java

src/main/java/de/tla2b/types/IDefaultableType.java

src/main/java/de/tla2b/types/IntType.java

src/main/java/de/tla2b/types/IntegerOrRealType.java

src/main/java/de/tla2b/types/PairType.java

src/main/java/de/tla2b/types/RealType.java

src/main/java/de/tla2b/types/SetType.java

src/main/java/de/tla2b/types/StructOrFunctionType.java

src/main/java/de/tla2b/types/StructType.java

src/main/java/de/tla2b/types/TLAType.java

src/main/java/de/tla2b/types/TupleOrFunction.java

src/main/java/de/tla2b/types/TupleType.java

src/main/java/de/tla2b/types/UntypedType.java

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

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