References: Resolves warning issue.
Doc: Fix spelling errors.
Shortened long lines.
Merge pull request #1459 from am11/master

References: Resolves warning issue
Merge pull request #1461 from epsitec/fix-contributing

Fix CONTRIBUTING.md spelling errors and shorter lines.
Release: Version 2.3.3.
Merge pull request #1467 from am11/master

Release: Version 2.3.3
Package: Read version from a const.
Merge pull request #1468 from am11/master

Package: Read version from a const