This is supposed to be more efficient

We're not supporting Python 3.2.

* for multiple commands, such as in
  ``'\n'.join((cmd, cmd2))``, cmd2 and beyond
  previously used a ``timeout`` of 1, instead of
  the specified or default ``timeout``.
* furthermore, the output of multi-command output
  was discarded, only the last-most command output
  was received.  Resolved by joining the result of
  ``self.child.before``.

Forgot to set ``echo=False`` when calling spawnu()
directly in replwrap.bash(), resulting in IOError
on SunOs:

    IOError: [Errno 22] Invalid argument: setecho() may not be called on this platform.

By providing our own bashrc which overrides PS1, we can have a
consistent prompt without breaking other customisations of bash that
people may want to keep, such as aliases defined in bashrc.

allow matching a regular expression,
use setUp and tearDown to putenv & getenv PS1, PS2
unset PROMPT_COMMAND