Base branch for automatic branch creation when working on issues

[pawel-kow]

Currently the feature branch when staring work on an issue is always created out of the default branch.

In case there are several "main" branches (for example for different versions or bigger features) one would want to create branch either out of the current branch, or have a configuration which branch should be taken as default.

The only solution right now is to create branches manually matching the pattern.