Added rounding logic to FlightPath class, when applying subs, to compensate for weird floating point
  arithmetic errors.  Adjusted it and Student class to round to 6 places, instead of 5.

  Added ability to filter by role in the User management module.  Also did some minor display tweaking
  to make things fit better.

  Fixed a minor bug in User module, where the list of students would select a major code if a search
  were performed.  Due to re-use of a variable name.

  Fixed a bug in CourseList and FlightPath classes where GPA and hours wasn't being calculated correctly,
  especially for subs split more than once.

  Added a new hook to AdvisingScreen class, after build_screen_elements(), so other modules
  can hook in and add to the screen once that function is called.  See advise.module's listing
  for hook_advise_build_screen_elements() for description and example of use.