Fixed a bug related to negative fixnum encoding (i.e. -1). -1 was
tree8590dfb1dfd2174a10be173f5fedc79202346914
-rw-r--r-- 10769 library.scm
-rw-r--r-- 16549 math.scm
-rw-r--r-- 87903 picobit-vm.c
-rw-r--r-- 112041 picobit.scm
-rw-r--r-- 31589 robot.scm