Rewrite WebGL code in regl

The time has come to 🔪 the gl-vis project.

These multiple small modules are becoming harder and harder to maintain. A lot of helper methods are currently duplicated across several modules - which is adding a lot 🍔 to our bundle size.

@mikolalysenko’s new WebGL framework regl solves a lot of long-standing gl-vis issues such as multiple scopes per gl-context and improved memory management.

I placed this issue on the v2.0.0 milestone because it might be a good opportunity to make the switch in-phase with bumping d3 to v4 but this is subject to change.

@dfcreative @monfera @bpostlethwaite

[dy]

regl-error2d, faster and w/o memory limitations. Should say working with regl is pure pleasure.

[etpinard]

scattergl v2 wishlist:

• plot 1e6 points in 1000ms
• fast updates (~ 100ms)
• reuse SVG cartesian axis/subplot logic and renderers
• share 1 gl context across all subplots on given gd (or even better 1 gl context per page)
• per-point support for marker size, color, symbol, opacity and line width, line color