Apply SIGINT restoration to new module layout

Apply SIGINT restoration to new module layout

This brings Markus Schmidt's v2.0.x fix into the master branch.  git did
not know how to apply this commit across branches.  Frankly, I don't blame
it, either.  The development branch uses multiple processes where the
stable branch has only one.  So, the one change needed to be applied in
two places to reach every executing process.

This is a combination of two commits on the stable branch:
"Ctrl+C on main window (restore signal handler)" and
"Expand comment for signal handler reset"

Signed-off-by: Sean Robinson <robinson@tuxfamily.org>