Fix MTA bug with Cut
Rethrow exceptions during unit tests

The error reporting message that was added gets in the way of
ensuring tests fail in a more reasonable way.  So if I can tell
the unit tests are running, just rethrow the exception.
Fix exception after AcceptAndGetNext

The "current" line cleared after accepting via AcceptAndGetNext
and we would crash trying to recall this current line.

I've changed how history search works after AcceptAndGetNext
to work in a more natural way so that arrow keys can be used
to recall commands near the accepted command instead of
searching for other commands with the same prefix.

Fixes #152.
Stop using static parameter binder

The static parameter binder is causing too many false errors
so I'm removing the checks it was doing.
Support exit process with Ctrl+D in Emacs mode

Added new function DeleteCharOrExit bound to Ctrl+D
in emacs mode.

Fixes #121.