v0.6.0

• Leading plus signs + are now stripped for siunitx notation within
  Markdown.

• Added amsmath, amssymb, and siunitx to template for LaTeX solutions
  export.

• Fixed a bug with error handling when Pandoc fails to export solutions (#47).

• For question groups, the value of pick is now allowed to equal the total
  number of questions (#44).

• Added support for Pandoc-style attributes on images:
  ![alt_text](image_file){#id .class1 .class2 width=10em height=5em} (#41).

• Executable code blocks now use PATH to locate executables under Windows, and
  thus now work with Python environments. Previously PATH was ignored under
  Windows due to the implementation details of Python's subprocess.Popen()
  (#34, #42).

• Added command-line options --solutions and --only-solutions to
  command-line application. These generate solutions in Pandoc Markdown,
  PDF, and HTML formats. Pandoc Markdown solutions are only suitable for
  use with LaTeX and HTML (#35).

• Added quiz-level options feedback is solution, solutions sample groups,
  and solutions randomize groups for customizing solutions. Added
  group-level option solutions pick for customizing solutions. Added
  question-level syntax involving ! for providing solutions.

• In quiz parsing, simplified question type handling and error checking.

• Fixed bug in calculation of total points possible per quiz.