Support JDK7 omitted exceptions

JDK7 adds the concept of an "omitted exception" which is related to the try with resources construct. These are still valuable, still part of the cause train.

JDK7 .printStackTrace presents omitted exceptions somewhat "side-barred", indented under the exceptions they were collapsed into. We could do the same, or use an alternate (dimmer) font for such exceptions.

Since we only present the stack trace of the deepest exception, even that may not be necessary.

Start by tracing the exception-rendering entry point that produces the deepest exception stack trace, then compare its behavior with JDK7 printStackTrace for omitted exceptions. Done means the handling of omitted exceptions is implemented with an agreed presentation, or the issue is clarified if the existing deepest-exception behavior makes it unnecessary.

Written by the indexing model from the issue text.