Span extensions running twice.

[Hampei]

I have an extension that adds a span around some strings, but adds the same string in again as well.
It gets run when creating the maruku object and again over the previously generated string when calling to_html, which is once to many.
I don't know if it worked differently in 0.6 or if it's just that spans where not being parsed for markdown before.

> m = Maruku.new("{{test}}")
=> md_el(:document, md_par(md_html("<span class='text_var' text_var='test'>{{test}}</span>")))
> m.to_html
=> "\n<p><span class='text_var' text_var='test'><span class='text_var' text_var='test'>{{test}}</span></span></p>\n"

MaRuKu::In::Markdown.register_span_extension(
  chars: (RUBY_VERSION >= '1.9' ? '{' : 123),
  regexp: /(\{\{)(.+?)(\}\})/,
  handler: lambda do |doc, src, con|
    m = src.read_regexp(TEXT_VAR)
    var_name = m.captures.compact[1]
    string = "<span class='text_var' text_var='#{var_name}'>{{#{var_name}}}</span>"
    con.push doc.md_html(string)
    true
  end)

[distler]

I don't know if it worked differently in 0.6 or if it's just that spans where not being parsed for markdown before.

See the resolution to Issue 31.