Pymod manylinux wheels built on travis

[thomaslima]

Hi Matthias,

Warning: Only merge this after #212 .

I apologize in advance for the long pull request. Even though the commits are long, the functionality changes are simple:

• I am generating pip wheels for linux using the manylinux1 policy. This makes pip install klayout in linux distros download pre-built images from PyPI.org. I had to fix a bug in the auditwheel project in the meantime. auditwheel repair could not figure out the library dependencies in klayout. I submitted a PR Test cases: Unwanted RPATH overwrite and Failing to patch internal non-py extensions pypa/auditwheel#134 Hopefully they will take it.
• I enabled ccache in the build steps to reuse most of the built objects between travis runs if the source code hasn't changed.
• I changed pya/__init__.py to better reflect how it behaves inside Klayout's app.
• I uploaded two versions to pypi.org in the process: klayout-0.26.0-dev9 and klayout-0.26.0-dev10.
• While I was doing all this, I documented my thought process in ci-scripts/docker/development_notes/README.md

Here's an example of what the travis builds look like now: https://travis-ci.org/lightwave-lab/klayout/builds/470707822

Best,
Thomas

[thomaslima]

Here are the wheels for this build: https://pypi.org/project/klayout/0.26.0.dev10/#files
Install with pip install klayout==0.26.0.dev10

[klayoutmatthias]

Hi Thomas,

thanks for the thoughtful comments. I'm still not friend with setuptools, but I hope I'll improve :-)

Best regards,

Matthias