Change readme to markdown, add formatting
Add links on Readme to nuget packages
Remove hidden overloaded method

Overloaded by optional param. No longer needed.
Add Optional param to Read method from TextReader

Add optional param based on the default of the method that it calls, and
remove the unneeded method covered by this param.
Add missing xml-comments
New DataTableBuiler.ReadString() method

Allows generating a DataTable from a string. Can provide line ending
(defaults to \r\n). Includes XUnit test.