Parse and Manipulate Changes Files

[ckunki]

Ticket #517 requests to describe resolved vulnerabilities in the changelog.

In order to simply this task, the current ticket requests to add a dedicated class for that:

• parse from raw text (input)
• render as raw text (output)
• check if a specific section is contained
• add or update a specific section
• remove or replace a specific section

Also in the past (e.g. ticket #505) an implementation has been added to include a report of dependency changes in the changelog which could benefit from a central changelog manipulation class, too.