kes Fix memory leak with storage ids in cats/sql_get.c

kes  Terminate watchdog earlier to avoid reference to released
     memory -- reported by Jason Austin.
kes  Move closing the database from jobq.c to the director daemon
     termination routine. This fixes memory leaks for shadow jobs
     (i.e. migration jobs).
kes  Free up the unique jobid chain items in migrate.c.  This fixes
     a memory leak problem.
kes  Convert some ugly looking for statements to use foreach_alist
     in findlib/find.c.  This will facilitate converting the structures
     to use dlist (for large include/exclude lists).
kes  Fix a bug in the btree.c and btree.h routines, then rename them
     rblist and add them to be built in src/lib.  Include some new
     methods written by Rudolf Cejka that make the code more readable
     (hides some of the ugly casting).
kes  Add set_next() and set_prev() methods which make the code much more
     readable. Also add a new dlistString class that facilitates storing
     strings in dlists.  To be used in the large include/exclude lists.
kes  Make some trivial modifications to lib/tree.h that use rblist
     rather than dlist for storing the tree links. This was suggested
     by Rudolf Cejka.  The result of this is that the restore tree now
     uses red-black binary trees rather than simple linked lists. This
     should give rather dramatic speed improvements for directories
     contining large numbers of directories/files (more than 10000).