Lots of work on exception handling, including tests for traceback printing....
Lots of work on exception handling, including tests for traceback printing.
We finally have some tests for various exception mode printing, via doctests
that exercise all three modes!
Also changed handling of sys.exit(X) to only print the summary message, as
SystemExit is most often a 'handled' exception. It can still be 100%
silenced via '%run -e', but now it's much less intrusive.
Added a new %tb magic to print the last available traceback with the current
xmode. One can then re-print the last traceback with more detail if
desired, without having to cause it again.
