fixed increment and decrement to work properly with AUTO_BIGNUM Rev: src/interpret.c:1.131 Rev: src/interpreter.h:1.16 Rev: src/object.c:1.86 Rev: src/peep.c:1.26 Rev: src/program.c:1.165 Rev: src/program.h:1.62 Rev: src/svalue.c:1.50