v0.17.0 keep up-to-date with recent pytorch code

What's Changed

• deal with none in patch by @youkaichao in #40
• update usage by @youkaichao in #41
• try to deal with irregular const by @youkaichao in #42
• fix the cpp guard by @youkaichao in #44
• pretty print guard by @youkaichao in #45

Full Changelog: v0.16.0...v0.17.0