Html endpoint

[dbolack-ab]

A possible solution for the HTML-only output using the existing sharePage logic rather than restoring the old printPage.

Solves #956
Possibly solves #661

• Test on phones to see if solves margin-*: auto readability issues, sort out how to remove margin styling
• Add to menu bar
• Discuss if a better path name ( embed? export? ) should be used.
• Verify works for embedding.

test using .../html/shareId

[calculuschild]

This puts new stuff into the sharePage, but then ignores almost all of the sharePage logic. If we have to basically bypass the whole sharePage output, that seems to me a sign that it really just needs to be its own dedicated page.

I think this might be worthwhile to just take the old /print page as a starting point, and then strip it down to the very minimum (doesn't need to deal with loading values from /new, etc).

[calculuschild]

By the way, I don't think this solves either of #661 or #956, though a plain HTML view was requested separately on Reddit.

My understanding from reading those issues is that they want a bundle of CSS + HTML they can copy and host on their own website, so more a download link than an HTML view. In any case, we should not encourage users hot-embedding our site; we are not a CDN to host files for other people's web pages.