Add style guide to wiki

[marcusfuchs]

Add style guide to wiki for contributions

[psteinhoff]

I think this is a nice summary for a possible workflow for contributions.
https://guides.github.com/introduction/flow/index.html

Forking a repo, working on an issue (comitting changes in short periods, perhaps in an specific branch) and sending the pull-request to AixLib will possibly be the best choice.

[marcusfuchs]

I think this is a good starting point for the discussion. As I understand it, the link @psteinhoff provided describes the concept of branching and reintroducing the changes into the master with a pull request. This seems like the best way to go. Yet, the question whether to open and work on the branch in RWTH-EBC/AixLib or in your own fork /AixLib is not addressed in the link and I think there are good arguments for both ways.

I slightly tend to suggest a standard flow of working on the branch in RWTH-EBC/AixLib. This would omit the additional steps of opening and keeping my own fork up to date. In addition, forking could be mentioned as a second option, as it does have advantages for larger individual development and there is no reason to refuse a pull request from such a fork.

[marcusfuchs]

Added a workflow description closely following the Annex 60 workflow. We can add a detailed style guide with version 1.0.0 (or earlier if applicable).