Added an interface for factories so all of them will use the same method name to generate objects
Merge branch 'feature/sy-interfaces' into develop
#7 interface for the registry added
#7 added the default implementation of the registry interface
#7 removed the StackInterface as it was kind of an ancestor of registry, mixed with entity handling
#7 unit tests added for Sy.Registry
Close #7 Merge branch 'feature/registry' into develop