fix: set white space after token

Bug fix

Summary

During the HTML serialization, a white space is set after each token

Not having set this let to the text nodes being displayed as one long text node.

Compliance to “Definition of Done”

• Unit tests passed
• Code reviewed
• Product Owner accepts the User Story

Changelog

• I added a statement to the CHANGELOG.

Version number

• I bumped the version number in build.properties.

Readme and general docs

• I updated the README (if applicable) and kept the docs up to date.

Closes

Closes #142 (closed)

/cc Mathias Göbel, Frank Schneider, Michelle Weidling