core-dumping bug fixed + more debug added

Rev: src/array.c:1.27
Rev: src/interpret.c:1.67
Rev: src/main.c:1.40
Rev: src/main.h:1.6
Rev: src/object.c:1.37
Rev: src/signal_handler.c:1.29
Rev: src/signal_handler.h:1.5
Rev: src/svalue.c:1.19