add ability to d3 vis to live-update min-intersection requirement

[deargle]

if include_min_intersection_selector=True is passed to mapper.visualize, then a number input is included at the top of the d3 vis which permits changing the min_intersection req for edges (links) to be drawn.

Currently does not get saved in the downloadable config file.

[codecov[bot]]

Codecov Report

Merging #231 (c24cb3a) into master (7dc4d0a) will not change coverage. The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #231   +/-   ##
=======================================
  Coverage   80.27%   80.27%           
=======================================
  Files          11       11           
  Lines         862      862           
  Branches      189      189           
=======================================
  Hits          692      692           
  Misses        138      138           
  Partials       32       32           

Impacted Files	Coverage Δ
kmapper/kmapper.py	89.71% <ø> (ø)
kmapper/visuals.py	85.52% <ø> (ø)

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[deargle]

No update to doc examples yet, because I'm afraid of the docs.

Also, demo gif:

[deargle]

Closes #211