in .po metadata caused a crash.

Also, removed some unnecessary code.

Backport candidate.

* call tearDown when Setup is called
* shutil.rmtree the root of the created directory instead of just the leaf
  directory
* set the LANGUAGE environment variable to what it was originally and not
  assume 'en'.

GNUTranslations constructor.

- Expose NullTranslations and GNUTranslations to __all__

- Set the default charset to iso-8859-1.  It used to be None, which
would cause problems with .ugettext() if the file had no charset
parameter.  Arguably, the po/mo file would be broken, but I still think
iso-8859-1 is a reasonable default.

- Add a "coerce" default argument to GNUTranslations's constructor.  The
reason for this is that in Zope, we want all msgids and msgstrs to be
Unicode.  For the latter, we could use .ugettext() but there isn't
currently a mechanism for Unicode-ifying msgids.

The plan then is that the charset parameter specifies the encoding for
both the msgids and msgstrs, and both are decoded to Unicode when read.
For example, we might encode po files with utf-8. I think the GNU
gettext tools don't care.

Since this could potentially break code [*] that wants to use the
encoded interface .gettext(), the constructor flag is added, defaulting
to False.  Most code I suspect will want to set this to True and use
.ugettext().

- A few other minor changes from the Zope project, including asserting
that a zero-length msgid must have a Project-ID-Version header for it to
be counted as the metadata record.

'en' in teardown().  This way hopefully test_time.py won't fail.

recent classobject.c change.  When calling an unbound method with no
instances as first argument, the error message has changed.  The
message now contains the class name, but the output text being
compared to is too generic, so skip printing it.

class-based APIs.

useless.  So the test of the dcgettext() function is removed.

cvs tree.  It creates the directory and gettext.mo file on the fly,
from the base64 encode binary data.