Csurf "subject:" entry/dropdown (left)

This entry contains the current subject.  The
dropdown contains a list of all the subjects in
the current $SUBJECTS_DIR, typically with
first3-last3 names (avoid spaces!):

  marser

Selecting a subject from this dropdown is
equivalent to:

  File -> Open Subject.

Entering text plus <Return> here pops up a list
of partial matches.  Glob-style patterns can be
used (but are not required).  This allows simple
searches:

  mar -> means find all names containing "mar"

All the subjects in $SUBJECTS_DIR are loaded at
csurf startup time.  To update the dropdown if a
subject has been added after starting csurf, use
File -> Update Subjects/Sessions or Cmd-u (Mac)
or Alt-u (Linux).

Since the csurf program stores configuration
information for the current subject in:

  $SUBJECTS_DIR/<subj>/scripts/csurf.dat

it will complain if you try to select a subject
directory in $SUBJECTS_DIR that does not contain
a "scripts" subdirectory.
