commonmark.js 0.18.2

• Fixed walker so that it stops at this.root, even when this is
  not the document root.
• Fixed typo (Ed Adams).
• Removed unused argument from processEmphasis (Robin Stocker).
• Shortened code for removing a sequence of delimiters, changing the
  links on the edges rather than dropping them one by one
  (Eli Barzilay).
• Code layout improvements for readability (Eli Barzilay).
• Dingus: rewrote without ACE editor for better accessibility
  and to fix layout in smal windows (#11).
• Optimize checking for final spaces in parseNewline (Robin
  Stocker). This yields a 5-10% speed improvement in make bench.
• Consolidated regex definitions (Robin Stocker).
• Return boolean from spnl and parseBackticks for consistency
  (Robin Stocker).
• Removed unnecessary check for hrule in parseListMarker (Robin
  Stocker).
• Return error status if tests fail.
• Use encode/decode from markdown-it/mdurl for URL
  normalization. This fixes cases like [link](http://google.com/?q=%3f)
  which was formerly wrongly converted to
  <a href="http://google.com/?q=%253f">link</a> (#9).
• Refactored test.js, adding smart_punct tests from cmark, and
  factoring out specTest function.
• Make unmatched double quotes left quotes with smart_punct (#14).
• Code cleanup in finalize.