message: Don't warn about Crowdin's plural forms
  Crowdin uses non-canonical plural forms for their POs (excessive,
  unused forms that must be translated, but are never actually used) and
  are not going to fix it, so just stop complaining about them.
diff: @@ -2375,7 +2375,7 @@ void PoeditFrame::WarnAboutLanguageIssues()
  }
  else // no error, check for warning-worthy stuff
  {
  - if (lang.IsValid() && plForms != lang.DefaultPluralFormsExpr())
  + if (lang.IsValid() && plForms != lang.DefaultPluralFormsExpr() && !m_catalog->IsFromCrowdin())
  {
  AttentionMessage msg
  (
  