refactor: use a src/ directory

[JustinBeckwith]

No description provided.

[codecov-io]

Codecov Report

Merging #105 into master will not change coverage.
The diff coverage is 100%.

@@          Coverage Diff          @@
##           master   #105   +/-   ##
=====================================
  Coverage      84%    84%           
=====================================
  Files           3      3           
  Lines          75     75           
=====================================
  Hits           63     63           
  Misses         12     12

Impacted Files	Coverage Δ
tools/prepublish.js	40% <ø> (ø)
src/load.js	100% <100%> (ø)
src/index.js	100% <100%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update d34a901...e7892ce. Read the comment docs.