To-one relationships should be optional in swift.
Merge pull request #239 from rokgregoric/to-many

[CHANGE] Removed to-many accessors from swift template (causing infinite loops). (Rok Gregorič)
Merge pull request #238 from rokgregoric/to-one

[FIX] To-one relationships should be optional in swift. (Rok Gregorič)
Make property optional only if to-one relationship marked as optional (swift).
Merge pull request #241 from rokgregoric/to-one

[CHANGE] Swift: make property optional only if to-one relationship marked as optional. (Rok Gregorič)
Added back to-many accessors (swift template).