reduced model, working on base version 2

...e/tudresden/inf/st/pnml/base/constants/PnmlConstants.java

src/main/jastadd/base/Navigation.jrag

src/main/jastadd/base/clauses/ExpressionParser.beaver

src/main/jastadd/base/clauses/expressions.jadd

src/main/jastadd/base/clauses/expressions.relast

src/main/jastadd/base/distribution/DistributedPN.jadd

src/main/jastadd/base/distribution/Filtering.jadd

src/main/jastadd/base/export/PrimitiveElementsConverter.jadd

src/main/jastadd/base/io/IoPN.jadd

src/main/jastadd/base/io/IoPN.relast

src/main/jastadd/base/parsing/PnmlParserInternal.jadd

src/main/jastadd/base/parsing/PnmlSignalParser.jadd

src/main/jastadd/base/parsing/ToolSpecificsParser.jadd

src/main/jastadd/base/transforming/PnmlSlicer.jadd

src/main/java/de/tudresden/inf/st/pnml/base/Main.java