Preparation for 0.3.0 release (fortran-lang#728)

Merge pull request fortran-lang#651 from awvwgk/bugfix-0.2.1

Bugfix release version 0.2.1

Merge pull request fortran-lang#631 from awvwgk/release-0.2.0

Preparation for 0.2.0 release

Bump stdlib version to 0.1.0 (fortran-lang#538)

- update changelog, add changelog to pages