New update method: the 'old' keys are saved for each records.
-rw-r--r-- 1857 Makefile
drwxr-xr-x - bfile
drwxr-xr-x - dfa
drwxr-xr-x - dict
drwxr-xr-x - include
drwxr-xr-x - index
drwxr-xr-x - isam
drwxr-xr-x - rset
drwxr-xr-x - util