Cchardet

- support Python 3.7

- enable [LTO](https://gcc.gnu.org/wiki/LinkTimeOptimization) for wheel builds
- update Cython

- fix that different results with different chuck sizes
- fix that assignments to nsSMState in nsCodingStateMachine result in unspecified behavior
- include COPYING in package

- add cchardetect CLI script ([30](https://github.com/PyYoshi/cChardet/pull/30))[\craigds](https://github.com/craigds)

- fix an issue where UTF-8 with a BOM would not be detected as UTF-8-SIG (fix [28](https://github.com/PyYoshi/cChardet/issues/28))
- pass NULL Byte to feed() / detect() (fix [27](https://github.com/PyYoshi/cChardet/issues/27))

- Improve tests