Extend matchers and add Scaladocs

[stringbean]

No description provided.

[codecov-io]

Codecov Report

Merging #1 into master will increase coverage by 6.66%.
The diff coverage is 100%.

@@           Coverage Diff            @@
##           master     #1      +/-   ##
========================================
+ Coverage   93.33%   100%   +6.66%     
========================================
  Files           4      5       +1     
  Lines          45     63      +18     
  Branches        8      9       +1     
========================================
+ Hits           42     63      +21     
+ Misses          3      0       -3

Impacted Files	Coverage Δ
...tware/purpledragon/xml/scalatest/XmlMatchers.scala	100% <100%> (ø)	⬆️
...la/software/purpledragon/xml/compare/XmlDiff.scala	100% <100%> (+20%)	⬆️
.../purpledragon/xml/compare/options/DiffOption.scala	100% <100%> (ø)
...software/purpledragon/xml/specs2/XmlMatchers.scala	100% <100%> (ø)	⬆️
...software/purpledragon/xml/compare/XmlCompare.scala	100% <100%> (+6.45%)	⬆️

---

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 97b5771...c4aa98c. Read the comment docs.