v1.6

This release of mmd adds support for link titles and code languages, adds
functions for controlling which markdown extensions are supported, and fixes
a number of parsing bugs.

Changes include:

• Fixed some parsing bugs (Issue #7)
• Fixed a crash bug in mmdutil (Issue #8)
• Code fences using "~~~" are now supported.
• Auto-links now properly handle preceding text (Issue #8)
• Inline styles can now span multiple lines (Issue #8)
• Links can now span multiple lines (Issue #8)
• Shortcut links ([reference]) didn't work (Issue #8)
• Fixed some issues with inline styles being incorrectly applied for things
  like "* *".
• The testmmd program now supports running tests from the CommonMark
  specification and/or from the CommonMark test suite (Issue #9)
• More CommonMark features (code languages, link titles, space-filled thematic
  breaks) and edge cases are now supported (Issue #10)
• Added new mmdGetOptions and mmdSetOptions functions to control which
  extensions are supported.
• Added new mmdGetExtra function to get the link title or code language
  string associated with certain nodes.

Enjoy!