Fixed bug in transition-position

Fixed bug in transition-position causing it to select the incorrect position in the haystack for many cases. This leads %geuss-offset to guess the incorrect offset often ignoring the existence of daylight savings time.

Test Case:
(local-time::transition-position 13 #(-15 -10 -5 0 5 10 15 20 25 30 35 40 45 50 55 60))

bugged ==> 6
fixed ==> 5

In CST6CDT zone:

bugged: (now) ==> @2013-06-25T12:44:50.789841-06:00
fixed: (now) ==> @2013-06-25T13:47:23.598036-05:00