Added package traversal
Put back in Data.Foldable instances
Fixed import
Fixed imports
Changed parseDocs' type

For better error reporting.
Fix code review notes
Merge pull request #40 from jspahrsummers/comment-errors

Changed parseDocs' type
Fix type signature style and document traversal functions
Expose all traversal functions, hide nesting parameter
Merge pull request #39 from jspahrsummers/decl-linear

Package traversal