feat(bss2): Support for "incremental experiments" and some cleanup of PyNN@0.12-related changes

We now support a builder pattern using pyNN.run(). This allows to construct single(!) experiments with changing stimulus dynamics/recording settings/parameter changes.

(Also: Some changes that were already available via 8.0-a2 have been cleaned up (i.e. passed internal review and CI).)

added 2 commits

• 5b978bec - feat(bss2): support for "incremental experiments"
• 407893ff - feat(bss2): enable new version

Compare with previous version

I added some depends_on('oppulance') for the new version, in the first pipeline it wasn't installed at all (and no tests failed? is that expected?) But maybe a more failproof way of dealing with this would be nicer?

merged