Allow component names to start with _

[yang]

Fixes #424

[alangpierce]

Thank you! One edge case that would be good to fix, but other than that looks good!

I can look into the test failures; they seem unrelated to your change.

[alangpierce]

@yang tests should be fixed now! Can you rebase? Also would be good to switch to the >= charCodes.lowercaseA && <= charCodes.lowercaseZ approach I mentioned, which also would likely be a little faster since it doesn't need to handle unicode.

[codecov-io]

Codecov Report

Merging #425 into master will decrease coverage by 0.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master     #425      +/-   ##
==========================================
- Coverage   80.09%   80.07%   -0.02%     
==========================================
  Files          47       47              
  Lines        5264     5040     -224     
  Branches     1174     1175       +1     
==========================================
- Hits         4216     4036     -180     
+ Misses        744      702      -42     
+ Partials      304      302       -2

Impacted Files	Coverage Δ
src/transformers/JSXTransformer.ts	92.61% <100%> (+0.07%)	⬆️
src/parser/index.ts	77.77% <0%> (-7.94%)	⬇️
src/index.ts	82.85% <0%> (-6.51%)	⬇️
src/computeSourceMap.ts	83.33% <0%> (-5.56%)	⬇️
src/util/getNonTypeIdentifiers.ts	94.44% <0%> (-5.56%)	⬇️
src/util/getTSImportedNames.ts	81.57% <0%> (-3.79%)	⬇️
src/parser/plugins/types.ts	91.66% <0%> (-3.34%)	⬇️
src/parser/tokenizer/readWord.ts	82.35% <0%> (-3.02%)	⬇️
src/parser/traverser/util.ts	86.2% <0%> (-2.17%)	⬇️
src/parser/traverser/base.ts	95.45% <0%> (-1.69%)	⬇️
... and 15 more

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[alangpierce]

🎉 thanks!

[alangpierce]

@yang Thanks, I just published as 3.9.6.