bytes2hex is -x switch for mndecode

mndecode.c

@@ -1,12 +1,18 @@
 #include <stdio.h>
+#include <string.h>
 #include <stdlib.h>
 #include "mnemonic.h"
 
-int main(void) {
+int main(int argc, char **argv) {
 	char buf[0x90000];
 	mn_byte outbuf[0x10000];
 	int buflen;
-	int n;
+	int n, i;
+	int hex_encoded_output = 0;
+
+	if(argc > 1 && strcmp(argv[1],"-x") == 0) {
+		hex_encoded_output = 1;
+	}
 
 	buflen = fread(buf, 1, sizeof buf - 1, stdin);
 	buf[buflen] = 0;
@@ -17,7 +23,13 @@ int main(void) {
 		return EXIT_FAILURE;
 	}
 
-	fwrite(outbuf, 1, n, stdout);
+	if(hex_encoded_output) {
+		for(i = 0; i < n; i++) {
+			printf("%X", outbuf[i]);
+		}
+	} else {
+		fwrite(outbuf, 1, n, stdout);
+	}
 
 	return EXIT_SUCCESS;
 }