Remove dev branch

[uvchik]

I would like to remove the dev-branch.

I think it is mainly confusing. We introduced it to contain examples of a not release versions. At the moment we do have different packages so that each package have to create its own non-visible branch with examples for upcoming releases. We do not have the same release date for all packages.

If anybody knows more about the actual state of the dev branch, feel free to do what every is necessary and remove it. I would just merge it into the master so that nothing gets lost.

[uvchik]

I also introduced the labels "windpowerlib", "tespy" and "solph" so that one can label issues and PR according to the package. I will add a label for each package that provides an example here.

[p-snft]

Agreed. But: Would it make sense to have the examples in the corresponding repositories instead? This would also allow to have new features and the corresponding example in one PR.