Modules like GDBM_File are fraught when you have potentialy many
readers/writers (like say in a long running forking daemon).  While they
might handle file locking properly, if any program holds the lock for too
long, others will not be able to write to the file.

This module solves the problem by doing a tie/operation/untie for each and
every operation.  NOTE THAT THIS IS ONE HUGE PERFORMANCE HIT.  Only use this
where all other methods fail.
