Fix catching of multiple errors.
Add -K to the default less arguments.

This allows Ctrl-C to be used to exit less.
Detect the pipe for the pager being closed and exit gracefully.
Be smarter about cleaning up the pager.

Register an atexit handler to make sure the pager gets cleaned up
correctly.  Also, attempt to preserve some mechanism for output by
duping the stdout and stderr, and restoring them in the atexit handler.
Finally, if stderr is also going to a terminal, route it through the
pager too.
Version 0.6.2: Avoid spurious failure from bare ``svnwrap`` invocation.

Newer svn clients return a failing exit code when invoked as ``svn``
with no arguments.  Detect and prevent this spurious error case.
Use pager for "help" and "helpwrap" commands.