Release 0.13

[FlorianRappl]

Types of Changes

Prerequisites

Please make sure you can check the following two boxes:

• [x] I have read the CONTRIBUTING document
• [x] My code follows the code style of this project

Contribution Type

What types of changes does your code introduce? Put an x in all the boxes that apply:

• [x] Bug fix (non-breaking change which fixes an issue, please reference the issue id)
• [x] New feature (non-breaking change which adds functionality, make sure to open an associated issue first)
• [x] Breaking change (fix or feature that would cause existing functionality to change)
• [x] My change requires a change to the documentation
• [x] I have updated the documentation accordingly
• [x] I have added tests to cover my changes
• [x] All new and existing tests passed

Description

(PR is already open, but it will not be merged in yet - description incoming)