Rewrite d3 wrapper to work with current version of d3.js and be better in general

[emilydolson]

This is the pull request for Elizabeth and Oliver's WAVES project, in which they are re-writing the d3 wrapper from the ground up to make it work with the new version of d3 while also making a variety of other improvements along the way.

[codecov]

Codecov Report

Merging #295 (f13b4b8) into master (223f54c) will decrease coverage by 0.32%.
The diff coverage is 78.51%.

@@            Coverage Diff             @@
##           master     #295      +/-   ##
==========================================
- Coverage   82.96%   82.64%   -0.33%     
==========================================
  Files         306      319      +13     
  Lines       37356    40565    +3209     
==========================================
+ Hits        30994    33526    +2532     
- Misses       6362     7039     +677     

Impacted Files	Coverage Δ
include/emp/web/CanvasShape.hpp	0.00% <0.00%> (ø)
include/emp/web/d3/transition.hpp	0.00% <0.00%> (ø)
include/emp/web/init.hpp	39.13% <0.00%> (+7.31%)	⬆️
include/emp/web/d3/svg_shapes.hpp	10.64% <6.85%> (ø)
include/emp/web/d3/selection.hpp	29.65% <30.29%> (ø)
include/emp/web/js_utils.hpp	43.91% <50.00%> (+40.27%)	⬆️
include/emp/web/d3/scales.hpp	67.64% <66.81%> (ø)
include/emp/web/d3/d3_init.hpp	71.15% <69.76%> (ø)
tests/web/d3/transition.cpp	93.33% <93.33%> (ø)
tests/web/d3/shapes.cpp	95.45% <95.45%> (ø)
... and 16 more

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