Rebaseline tests whose results have changed.
Merge pull request #203 from mikewest/tests

Rebaseline tests whose results have changed.
Properly use prefixlen for raw <pre> lines.
Add an 'Indent' configuration option.

This patch adds an 'Indent' key which can be set in a document's
metadata section in order to configure the number of spaces that
Markdown expects as an indent. If the value isn't set, it
defaults to 4.

Tabs are, of course, accepted regardless.