New release and follow-up tasks

[bittner]

We're close to a new release, and it makes sense to discuss a few thing before that happens:

• We now have v2.6.0 and the current master holds code that has removed any support for Python 2.7. I would guess that qualifies for bumping the version number to v3.0.0 (rather than v2.7.0). – Any other opinions?

For what it's worth to think about after the release:

• The Piwik module has a deprecation notice for some time. After the new release it probably would be a good move to remove that module from the code base, finally.
• We now have 3 Google Analytics implementations (legacy, gtag, js), and we should probably start to deprecate at least the legacy option. Maybe we can consider consolidating all solutions into a single Google Analytics module, as discussed in #28.

[bittner]

The Piwik module was removed via PR #213. :bomb: