Move forcing logic out into its own file for easier re-use by other parts of the system
Jacoby transfer accepts are not really artificial bids.  They're not forcing, and doubling them is not negative.
Fix forcing-bid detction and make NaturalPass only apply when not forced to bid
Learn how to pass after preempts, and add one more None from autobid-for-none
Remove a FIXME from SecondNegative and add a test case to make sure it's fixed