documentation of the Exception Hierarchy and attributes.

also a bit of general cleanup around error handling in conductor.
Hopefully to be polished an abstracted to leap.base with time.

not all errors are converted (and the old with_errors/ignoring
errors) are still there, but we should be using this style of handlers
from now on.

wrapping up with this pseudo-feature for now. as we work on individual
features we can mimick the exceptions that are working.

idea is that we define user messages in the exceptions,
and queue them during (conductor) checks.

user facing dialogs get constucted from exception attrs.
if critical, log as such and exit.