Sling.js 21.0.0

• Change setTimeout and setInterval behavior. We no longer try to patch these functions and we no longer try to provide a "detached" alternative.
• Bring automated test count to 202.
• Do not add duplicate destroy functions to global array.
• Add logic to ensure slOnDestroy is called if the tag name is the same but the element is being recycled.
• Add logic to ensure slAfterInit is called if the element is being reintroduced to the DOM with changes.
• Add logic to ensure slOnInit is called if the element is being reintroduced to the DOM with changes.