Things to do:

- Optimizing tarballs?
- gifrecolor?
- jpgstrip?

- scripts/zip2tarcat does not run under python 3:

    $ python3 scripts/zip2tarcat test.zip > test.tar
    Traceback (most recent call last):
      File "scripts/zip2tarcat", line 86, in <module>
        tarf.close()
      File "/opt/anaconda/envs/py33/lib/python3.3/tarfile.py", line 1727, in close
        self.fileobj.write(NUL * (BLOCKSIZE * 2))
      File "/opt/anaconda/envs/py33/lib/python3.3/tarfile.py", line 453, in write
        self.__write(s)
      File "/opt/anaconda/envs/py33/lib/python3.3/tarfile.py", line 461, in __write
        self.fileobj.write(self.buf[:self.bufsize])
    TypeError: must be str, not bytes
    Exception TypeError: 'must be str, not bytes' in <bound method _Stream.__del__ of <tarfile._Stream object at 0x7fb68696ec50>> ignored

    For this reason only python 2 is accepted, see autoconf/configure.ac, line 137.
