Defer render to requestAnimationFrame() to avoid unnecessary rerenders

[patricknelson]

Defer render to requestAnimationFrame() to avoid unnecessary rerenders until time to paint (particularly if already disconnected). Came up in sveltejs/svelte#8377 (comment):

In my testing, I noticed that when running as a deferred module, it saved from pointless renders that would been eventually disconnected/reconnected anyway. However, the biggest improvements (at least on avoiding wasted rerenders) were in using iife or umd (running early prior to parsing): There were lots of disconnects but also it was able to defer "just in time" during DOM mutations so that it only renders the 1 time prior to repaint, which helped a bunch.

Tasks:

• Defer Svelte component rendering to rAF
• Fix broken unit tests which rely on synchronous rendering (i.e.: literally every single one of them)
• TODO: Consider making this optional. If so, default enabled or disabled? If so, doc in README.md.
• Create new unit tests to validate the new deferred rendering functionality is working properly
• Update version, bump minor ver

[patricknelson]

Closing. Will be made irrelevant once the PR for issue #10 is applied, since the solution to that utilizes renderAnimationFrame() to queue rendering in all circumstances. Keeping note of this PR though since it addresses issues with unit tests.