3.9.0 - Follow the Rules

Add

• A default option in KingfisherManager to let users set a global default option to all KingfisherManager related methods, as well as all UI extension methods. #674

Fix

• Now the options appended will overwrite the previous one. This makes users be able to set proper options in a per-image-way, even when there is already a default option set in KingfisherManager.
• Deprecate requestsUsePipeling in ImageDownloader since there was a typo. Now use requestsUsePipelining instead. #673
• Some internal improvement for private APIs.