(cargo-release) ndarray-stats version 0.3.0

0.2.0 release (rust-ndarray#36)

* Use v0.8.0 for itertools

* Update version number

* Add release notes

* Nitpicks - we now have a solid amount of routines implemented

* Add links

* Update version in Cargo.toml example

* Add summary statistics to brief menu

* Add some info directly in the README

* Add ndarray link

* Drop ErrorKind

* Add a note on extension traits on the changelog

* Rearrange 0.2.0 changes

Release 0.1.0