Update to 0.20.3. Set LICENSE to gnu-lgpl-v2.

0.20.3
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- Bugs fixed in this release:
    Bug 583129 - [python] allow passing None as command or directory option
    Bug 583078 - [python] allow passing of environment as a dictionary

0.20.2
=======
- Bugs fixed in this release:
    Bug 567064 - Work around buggy iconv

(wiz)