Up version number

Update readme
Add packagist images for license and stable version

Update changelog and update version number to 1.5.6

Update tested up to 4.0
Updated copyright to Yoast BV instead of Joost de Valk
Made readme.txt slightly spammier, to function better within WP.org's search.

Ugh, bugfix.

Update changelog and version bump

Push version 1.5.5.1

Push 1.5.5, update changelog.

Update readme + version bump

Add changelog and version bump.

Removed extra linebreaks from changelog

Version bump to 1.5.3.3