Optimized workgroups

The Contao workgroups have been enhanced by multiple new members:

• Christoph Wiechert (Psi) will contribute to the workgroup "core development".
• Christian Schiffler (Xtra) and Tristan Lins (tril) will collaborate in the newly founded workgroup "extension repository".

We thank the new members for their willingness to contribute and wish a lot of engery and fun working on new ideas, suggestions and solutions for Contao and its community.