Implement in-table markup.

Specifically, the following are allowed:
 - Ordered lists
 - Unordered lists
 - Code blocks
 - NoWiki blocks
 - Lines of text.
Don't break the last list item in a table
Allow table cells to contain multiple InTable nodes, and define START for table cells to be whitespace-insensitive
Merge pull request #26 from Barrucadu/table-markup

Allow various wiki markup in table cells.  https://jira.int.corefiling.com/browse/REVIKI-341