chore: less java interop

[erdos]

Use Clojure built in functions instead of direct Java interop calls where possible.

[codecov]

Codecov Report

Merging #130 (890ada9) into master (944d2d7) will decrease coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #130      +/-   ##
==========================================
- Coverage   93.04%   93.02%   -0.02%     
==========================================
  Files          25       25              
  Lines        1897     1893       -4     
  Branches      108      108              
==========================================
- Hits         1765     1761       -4     
  Misses         24       24              
  Partials      108      108              

Impacted Files	Coverage Δ
src/stencil/process.clj	74.41% <ø> (ø)
src/stencil/cleanup.clj	93.47% <100.00%> (ø)
src/stencil/merger.clj	99.05% <100.00%> (-0.03%)	⬇️
src/stencil/model/style.clj	98.27% <100.00%> (ø)
src/stencil/postprocess/html.clj	85.96% <100.00%> (ø)
src/stencil/postprocess/images.clj	100.00% <100.00%> (ø)
src/stencil/postprocess/list_ref.clj	92.79% <100.00%> (ø)
src/stencil/tokenizer.clj	96.72% <100.00%> (ø)
src/stencil/util.clj	98.68% <100.00%> (ø)
... and 2 more

---

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 944d2d7...890ada9. Read the comment docs.