Use case: do not offer "outdated" components in selection

[leoselig]

When a component is no longer maintained it is annoying to still have it displayed in the available component options. While the component entry is still needed in the .strangelogrc to be able to compile older changelog entries, it could be configured to no longer be offered when adding new entries.
This is somewhat related to #16.

Possible solution

Transform .strangelogrc format to something like this:

path: ./changelog
components:
  component1:
    title: "First Component"
    enabled: true
  component2:
    title: "Unmaintained Component"
    enabled: false