import grouping/ordering consistency

[brendansudol]

@jeremiak -- i want to propose a pattern/standard for our file imports:

• 2 groupings: externals, relative
• within each, we alphabetize according to the module name (as opposed to the function(s) names. i think this has a few benefits: 1) it keeps related things together (for example, d3-array, d3-scale, etc., regardless of what the specific functions we import from those libraries are) 2) it means that if we change the name of a function that we import (or if we update which functions we import), we don't have to move the line that it's on.
• for relative imports, we group and alphabetize according to folder depth (i.e., first within same folder, then within ../foo, then ../foo2, then ../../bar...)
• 2 lines after last import to better separate from main code

let me know what you think! if you like this, i'll update the remaining files :)

[jeremiak]

I like it! Please keep updating :)

[brendansudol]

awesome, thx!