Add PlantUML output format

[k1LoW]

[codecov]

Codecov Report

Merging #106 into master will decrease coverage by 0.18%.
The diff coverage is 65.38%.

@@            Coverage Diff             @@
##           master     #106      +/-   ##
==========================================
- Coverage   71.64%   71.46%   -0.19%     
==========================================
  Files          11       12       +1     
  Lines        2007     2057      +50     
==========================================
+ Hits         1438     1470      +32     
- Misses        430      444      +14     
- Partials      139      143       +4

Impacted Files	Coverage Δ
drivers/sqlite/sqlite.go	87.35% <100%> (-0.04%)	⬇️
output/plantuml/plantuml.go	64.7% <64.7%> (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 243a41c...07d4f78. Read the comment docs.