Yosys 0.9 is a major release with ground-breaking new features. Most significantly,
it offers much better support for commerical FPGA targets, more formall verification
functionalities, added a python plugin, and many others. For a complete list of
changelog, please see https://github.com/YosysHQ/yosys/releases/tag/yosys-0.9

• passed all cases in make test;
• install, run example in examples/osu035 with make, see result file example.edif.
• run example in examples/python-api, check if it produces a plot.