• Require at least one nonspace character in a link label (#322).
• Require replacement (rather than omission) of U+0000 (#327).
• Clarified that entities resolving to U+0000 are to be
  replaced by U+FFFD (#323).
• Removed statement that what counts as a line ending is
  platform-dependent (#326). We now count \r, \n,
  or \r\n as a line ending regardless of the platform.
  (The line ending styles can even be mixed in a single document.)
• Defined "space."
• Revised "non-space character". Previously a non-space character
  was defined as anything but a space (U+0020). Now it is anything
  that is not a whitespace character (as defined in the spec).
• Clarified that tab expansion is a preprocessing step (#330).
• Clarified lazy block quote examples (#328).
• Clarified precedence of indentation that meets conditions for
  both list item continuation blocks and indented code.
• Added a test case with # directly followed by a letter
  (not an ATX header).
• Added two test cases illustrating that a list at the
  outer level can have items that are indented by more
  than four spaces (see commonmark.js#42 and
  http://talk.commonmark.org/t/odd-list-behaviour/1189).
• Fixed typo in emphasis examples.