Next iteration of x-element (soon to be 1.0.0).

[theengineear]

This closes #68, closes #67, closes #66, closes #57, closes #46, closes #42, closes #36, closes #31, closes #30, closes #28, closes #26, and closes #25.

This is a clean version of #58 — that PR began as an exploration and turned into a promising candidate for our initial 1.0.0. Since the discussions got lengthy in there, I decided to start fresh with a better branch name and a clean slate.

Significant changes:

• Static analysis is done up-front, once.
• Anything that can be validated statically throws errors
• Environment / runtime errors console.warn (e.g., inherited property shadowing, data-* attributes, etc.)
• Almost all of the XElement interface is static.
• observer >> observe is now a function (proper context is maintained if it's a constructor method).
• computed >> input + compute. compute is now a function. input is an array of property names which will be resolved to arguments at runtime and passed to compute.
• value >> initial + default. initial is used if initial value is nullish. default is used if property value is ever nullish.
• Type coercion is no longer done on set.
• Errors are thrown when you set a value with an incorrect type in the runtime.
• Concept of readOnly is first-class.
• Concept of internal is first-class.
• Internal setting/getting and read-only setting can be done via the .internal proxy.
• Computed properties are now lazily evaluated.
• Observation, reflection, and computation are no longer synchronous. Importantly, this allows us to set properties one-by-one and then get a single compute at the end.
• Concept of a "render root" is now supported via createRenderRoot.
• We always allow computation of computed properties before any arguments are defined. Previously, we had questioned that approach.
• Swapped the order of values in observe callbacks to be value, oldValue — it was previously oldValue, value.
• Order of operations are now compute, reflect, render, then observe.
• Listener logic has been improved and interface is now a function, not a string.
• All callbacks are bound to the constructor (e.g., compute, listen, observe, etc).
• Coercion of null and undefined to '' is removed, the underlying templating engine takes care of this for us.
• Deserialization of anything other than [Boolean, String, Number] now throws a halting error (e.g., setting an attribute for a property that is of type: Object).

[theengineear]

FYI @klebba — I think we're finally ready to merge this!

[theengineear]

Note — we will probably bump to 1.0.0-rc.41 before finally moving to 1.0.0. The important part is that we should be clear to merge this in and release 👌

[klebba]

@theengineear awesome work!