dx attribute properly calculated; hooray, Internet Explorer is working!

- switching from tracking “previous” computed width to tracking the
“new” one – the difference is whether we’re storing the width
computation with the newest overflow word added. Obviously it’s more
accurate to track the one that matches the substring content.
- Removed a debugger function since it isn’t necessary anymore
- With the above changes, we can now calculate dx offsets properly for
Internet Explorer! It’s working!
- Changed text on front page, removing sections that state that
Internet Explorer isn’t working properly.
- Removed code comments in JavaScript file stating that Internet
Explorer isn’t working
- Added my own credits and a link to D3 documentation to comments at
the top of the JavaScript file
- Switched off force_wrap_method flag so it’ll rely on browser
detection.