Utility Classes to invoke yeti compiler from java

The eval module makes it easy to use the yeti-compiler from yeti. However for embedding in another JVM-program written not in yeti, or for integration with build-tools etc it would be easier if there was also a pure-java(lang) interface, because Java is of course the langauge with which all other JVM langauges work best.

So I added CompileUtil and EvalUtil which are JavaBeans which can be used to compile/eval yeti and internally invoke the eval-module's functions.

I also think it would be useful if these come with the yeti.jar similar to the YetiTask.