WIP: do NOT merge

@wmhilton This is NOT the snack sized version. I am still working on that ...but I surely appreciate a quick feedback about the general approach

Modularizing jus

@zeke I think, I nailed.

• Removed the parse and render operations from jus (now jus is free to add any parsing/rendering libraries at will!)

• Created npm contexter. This PR has a new dependency npm contexter (and dropped some others not needed anymore)

• jus.js gets very simple (and could be simpler by using other optional events)

Not looking for merge approval this PR is for review convenience

• all tests pass OK
• still backwards compatible, tested with:
  • jus.js.org
  • zeke.sikelianos.com
  • acrophony

Test drive with contexter-cli

...also created npm contexter-cli for test drive the library

It starts a server to show the dir to context in action

contexter library could be extended through plugins

• to different file types ( layouts, pages, stylesheets, customTypes, ... )
• to different context object formats ( like snakecased keyName, deeper or shallow structures, ... )
• to any file process like parse, render, minimize, write, extract, ...
• in any flavor like (marky-markdown-lite, next-css, ...)