Set strand to 1 if not defined in object
requested to merge github/fork/thibauthourlier/hotfix/simplefeature_strand into feature/ensembl_friendly
Created by: thibauthourlier
When the Otter XML is created, it wants strand to be set for every object but some Ensembl objects do not have their strand set as the strand does not matter in some case. So we just set it to 1 for simplicity
It may not me useful for human and mouse but it is needed when working on new species