Feature/#159 annotations performance part 1: refactoring

Feature

Summary

This MR provides a refactoring of the annotations in order to separate concerns and make things a little bit faster by e.g. avoiding unnecessary function calls.

❗ This is only part 1 of solving #159 (closed). Part 2 aims at creating the annotation pages after installation and saving them so that the REST API can request a static page instead of having to compute the annotations all over again. Since the motifs are more pressing at this point, we decided to postpone the second part.

Compliance to “Definition of Done”

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

Documentation

• I updated the README (if applicable)
• I provided my functions with appropriate documentation
• I updated existing documentation

Tests

Are we able to test this new feature?

• Yes, everything can be done via unit tests.

Changelog

• I added a statement to the CHANGELOG.

Version number

• I bumped the version number in build.properties.

/cc Mathias Göbel, Frank Schneider, Michelle Weidling