Use morphdom

[shawnbot]

This started as an attempt at using virtual-dom, but then I came across morphdom and fell in love, so I used that instead. Most of the previously pending tests under incremental-dom have been fixed in this transition, with the notable exception of events (which are still undocumented, and obviously broken). There are also a bunch of new unit tests for the underlying code components, including a native DOM implementation of virtual-dom's "hyperscript" (h()) function.

In this PR:

• Move the class and style transforms to h()
• Cursory tests for element and attribute namespaces
• Major reorganization of functions, refactoring
• Linting with eslint
• Figure out namespace awareness in morphdom: SVG / NS Support patrick-steele-idem/morphdom#34
• Basic support for event listeners!
• Proper tests for element namespaces (e.g., preserve <svg> inferred namespaceURI)
• Proper tests for attribute namespaces (e.g., preserve xlink:href)
• Consider just using hyperscript, pending an investigation into its namespace support
• Add tests for <t-template>??

[shawnbot]

Oh, and: the full JS build (including document-register-element) is now 4K smaller at 20K!

[shawnbot]

Another nice thing about using the h() signatures is that it will be much easier to either swap out morphdom later if need be, or even to offer the ability to add a compatibility layer with virtual-dom.