Open items for future PRs related primarily to `table`

[monfera]

• add event callbacks to table Table view - squashed #2052 (comment) including plotly_hover and plotly_click events on the cells Table view - squashed #2052 (comment)
• roll back gup utils to parcoords: Table view - squashed #2052 (comment)
• get rid of camelcased classnames (use dashed) and put all classnames into constants.js: Table view - squashed #2052 (comment)
• discuss and plan cell editing and possibly other related functionality (request, reply)
• represent full table state via attributes (in) and callbacks (out) such that users can specify and/or receive, in logical units (row item) where we are in scrolling; similar full state representation for other interactions such as column drag&drop Table view - squashed #2052 (comment)
• put back valign (used to be there but needs a bit of work to handle cases of LaTeX etc.)
• do more to avoid wrapping: initial render should try to render straight away (no wrapping) and iff it breaches constraints, wrapping is invoked - this makes the current 2-step process into a 3-step process but CPU upside is big if no or few cells need wrapping (worth optimizing for the plainer case and negligible cycle loss even in the worst case)
• support individual border lines in addition to boxes; maybe border collapse?
• Support for 1D header values Table view - squashed #2052 (comment)
• Better handling of MathJax fill color styling Table view - squashed #2052 (comment)
• Support header.format scalar value https://github.com/plotly/plotly.js/pull/2052/files#r142410512
• Reuse plots/font_attributes.js https://github.com/plotly/plotly.js/pull/2052/files#r142410981
• Move <clipPath> to fullLayout._clips https://github.com/plotly/plotly.js/pull/2052/files#r142418318
• Jasmine tests
• Checking for render glitch (high speed scrolling and then stopping) and fixing it (issue found by @rreusser )
• More defaults.js logic to let users make do with fewer attributes, for example,
  • lines shouldn't be needed,
  • missing values (fewer or shorter vectors) could be filled with ""
  • cell heights should have the minimum of 2x the lowest font height in the row
• [ ] Fix scrollwheel scrolling issues in IE and FF now in table rows disappear on scroll in IE #3986
• At least one more mock
• Fix dominant-baseline / alignment-baseline related issues found by @alexcjohnson
• Look into the vertical alignment issue on CI in cells with wrapped text (looks fine in the wild; issue found by @alexcjohnson ) or await the switch to the Electron based tester by @etpinard

[etpinard]

@monfera Ok if I change the issue title to table open items? There's probably going to be a few other ones.

[monfera]

PR #2064 in for "Checking for render glitch"

[monfera]

"Better handling of MathJax fill color styling" was done in the original PR

[monfera]

PR #2065 for "Roll back gup utils to parcoords" (also, Sankey)

[monfera]

PR #2067 for "Get rid of camelcased classnames (use dashed) and put all classnames into constants.js"

[monfera]

@etpinard is there anything special to pay attention to, when putting the clippaths into fullLayout._clips? An aside: does it serve a technical goal, or is it more of a structuring convention?

[rreusser]

@monfera This perhaps: https://github.com/plotly/plotly.js/blob/master/src/components/drawing/index.js?utf8=%E2%9C%93#L759-L779

[monfera]

"Move to fullLayout._clips" - discussed that it's deferred until further discussion