Word containing two underscored result in Italic style

[DenisDuev]

For example having a word_contains_underscore:

• In Github is displayed ok: word_contains_underscore

  word_contains_underscore

<p>
  word_contains_underscore
</p>

• in gomarkdown the "contains" text is transformed as italic

  wordcontainsunderscore

<p>
  word<em>contains</em>underscore
</p>

See Babelmark

[ivanspasov99]

Same problem here @kjk

[miekg]

parser.NoIntraEmphasis https://github.com/gomarkdown/markdown/blob/master/parser/parser.go#L22