Add WriteHTMLForTraceDataToFile method.

Add WriteHTMLForTraceDataToFile method that allows creating trace viewer in html directly from trace data. 
I'm not a fan of the duplication going on here. It's going to lead to bugs (like the missing title in the WriteHTMLForTraceDataToFile above).

What about doing something like, make WriteHTMLForTraceDataToFile take an array of trace_data and do all the actual generation work. Then the WriteHTMLForTracesToFile just takes trace_filenames, reads the contents of the files into an array, and passes to WriteHTMLForTraceDataToFile?

That would keep all of the project, loading and generating code in one place.