Bug in latest version of MADivsRenderer..

Keith -- I was trying out your MADivsRenderer this evening and found that if my description class has no cssClass specified, that the following causes problems when the call to "(self classFor: aDescription)" returns nil.. It then tries to append "clear" to the list and that gets me a DNU.. It took me a while to track it down as I initially thought it might be a general Migritte issue.. Anyway, MAComponentRenderer>>classFor: has a call to #reduce at the end and if the class list is empty it returns nil which is where the initial nil is coming from. I checked to see what Squeak has for the #reduce: method and it also returns nil when the OrderedCollection is empty -- so this bug should be reproducible on Squeak as well.. I suppose one work-around would be to change MAComponentRenderer>>classFor: to check if it gets nil back from the reduce call and not return a nil object or perhaps something else like changing MADivsRenderer>>renderContainer to check the return value of #classFor: to see if it gets a nil back and if so create a string object.... comments/suggestions welcome..