Mark exception values in the evals tab as such

[ordnungswidrig]

Exceptions raised during evaluations go to the val column in the eval history table. This is a useful feature but they should be annotated or highlighted as error values.

[puredanger]

Actually beyond this, we went to a lot of trouble to make all these new exception messages in Clojure 1.10 and rebl does not make or display them! Would be great to have these show up. (-> throwable-data clojure.main/ex-triage clojure.main/ex-str)