Add stack_print(stack) function

Addresses #12 (closed)

stack.c

@@ -16,3 +16,11 @@ void stack_peek(stack s, int *value){
         *value = s.data[s.top];
     }
 }
+
+void stack_print(const stack s) {
+	printf("          TOP\n--------------------\n");
+	for (int* spot = s.data + s.top; spot >= s.data; --spot) {
+		printf("%8d |  %12d\n", spot - s.data, *spot);
+	}
+	printf("--------------------\n          BOTTOM\n");
+}