Several changes to move towards the same data structures as the
cbb 0.50;

- Now uses load_cats() (used to open the DBM file manually)
- Removed unused "is-it-older()" function
- Added dbm file for %ACCLIST - list of accounts
- Removed a pile of dbmclose() statements that caused perl warnings
- Added get_TXNS, put_TXNS, delete_TXNS to centralize access to the
  transaction dbm files.
- Created zeroth_TXNS(), next_TXNS() which probably ought to be
  replaced; next_TXNS() is a thinly disguised "each" statement.
- Added adj_bal(), which centralizes access to the balance dbm files.
  (BIG improvement.)
- Month format changed to YYYYMMDD.

- clearos now uses put_TXN(), thus handling balance changes nicer, and
  deletes transactions marked using "D" for deletion.

- createcat (create category) now has the -d option so that categories
  can be deleted.

- deltxn now marks transactions for deletion, leaving the deletion
  task for clearos.

- importqif now handles all sections of a .QIF file, ignoring those
  parts (investments, account lists) that it doesn't know how to
  interpret.

  Some time down the road, it may learn how to do them too.

- makeacct now puts an entry into the "acclist" file, as well as into
  the category list

- report is a new function that creates a summary.  It's buggy at this point.