Envisage to use groups instead of baselines

[jecisc]

I see that the different parts of PetitParser2 are managed via differents baselines. This has two negative impact IMO:

• It breaks the usage of branches. For example if I load PetitParser from the branch #myFeatureInDev, I'll get PetitParserCore from master and not from my branch
• It wakes it harder to build different groups. For example, I do not want the benchmarks in my projects, but it's hard to do a PR in this state to be able to load PP2 without them.

I am wondering why baselines are used instead of groups? PetitParser 1 is currently using groups and it works well.

[kursjan]

Perhaps @chisandrei can answer the question.