Release 0.2.3

Publish to pypi. No code changes.

Version 0.2.2

* Modernize packaging.
* Fix links to point to github.
* Fix deprecation warnings (Tobias Kaiser).
* Fix handling of invalid dates in GDSII files.

Version 0.2.1

Release 0.2

Version 0.1.1

Adds encoding declarations to scripts, otherwise they cannot be
executed with python 2.6.

Add long description