create new user overwritable operator methods for <,==,>,<=,=>,<==>

as not everything we want to let <,==,>,<=,=>,<==> operate on is a total order, it would be nice to have one of these defined only. Also the current solution with Comparable seems to lead to many problems, because Comparable itself is thought to be used with an exact counter part, but we might want to let it work on other classes as well. for this we should go away from Comparable. I would suggest we write a single method with a bitfield containing flags for <,> and ==. Then the user can throw an exception if a flagged operation is not available, also he can implement only < (100) or > (010) or == (001) or <= (101) or =>(011) or <=> (111). the way to keep backwards compatibility with this would be to add a compareTo method that uses the bits 111.. Well needs more discussion