Add first chapter on debugging
Add line numbers to all error messages if available!
Update to latest skulpt
More on introductory debugging
More Examples of common error types.
Merge branch 'refs/heads/debugging'
add showtitle and hidetitle options
Merge pull request #201 from isaacdontjelindell/reveal-directive

Add showtitle and hidetitle options to reveal directive
merge with master
First draft of debugging intro chapter.