view_article.html:
- lots of changes to the javascript:
  - removed intermediate link, so the links are no longer arcs, now straight lines...this improved performance especially with the marker
  - added an arrow marker to show the direction of the article reference
  - fixed the main article node in the center
  - fixed the 1st level reference nodes radially around the main article node
  - changed the force parameters to force the 2nd level nodes away from the center (high charge, no gravity)
  - dynamically apply the link strength based on the source node
  - added zoom and panning functions
  - automatically calculate the zoom for large graphs, seems to be working fairly well