Fix css class selection for Scenarios and Scenario Outlines in html formatter.
Extract a dom id from the file and line number of table row.
Extract out a DataTableRow and a TableRow for the Report Adapter.
Data table from step now prints correctly from html formatter.

This is a bit ugly as there is a switch based on legacy useage. I am not sure
what to do about it at this stage or if a similar issue has been delt with.
Extract Ast classes into constants.
Merge pull request #532 from tom025/new-core

Get tests for html formatter passing.