Allow to show/hide comments of particular levels
CPAchecker SMG already issues many notes of level 1 for error traces. Soon it can also start to issue comments of other levels as well. I suggest that comments of level 3 will be useful for developers of verification tools, so, it has sense to hide them by default, but there should be an ability to show them. Ditto for comments of level 2 since starting from some point users can become aware about corresponding assumptions, and they may want to hide them to reduce the error trace size.