UI Improvements, graph depth, topK WIP as follows:

 * General improvements:
   * Show a sample of nodes by default, not all of them
 * UI improvements
   * Ctrl-F to search for node
   * Visual improvements for section sub-titles
   * Unobtrusive, blue combo-boxes
 * Work-In-Progess:
   * Allow user to select graph drawing depth
   * Top vertices by degree