Fixed -z option argument parsing; fixes issue #127

Makefile

@@ -1,4 +1,4 @@
-VERSION = git-20140111
+VERSION = git-20140115
 
 PREFIX    = /usr/local
 MANPREFIX = $(PREFIX)/share/man

options.c

@@ -147,7 +147,7 @@ void parse_options(int argc, char **argv)
 				break;
 			case 'z':
 				n = strtol(optarg, &end, 0);
-				if (*end != '\n' || n <= 0) {
+				if (*end != '\0' || n <= 0) {
 					fprintf(stderr, "sxiv: invalid argument for option -z: %s\n", optarg);
 					exit(EXIT_FAILURE);
 				}