Support combination use of tdfiglet -x and -r options

e.g. to use only the first font (index 0) from a randomly selected font file.

exec/load/tdfonts_lib.js

@@ -84,7 +84,7 @@ function loadfont(fn_arg) {
     try {
 
 		const sequence = "\x55\xaa\x00\xff";
-		if(this.opt && opt.random)
+		if(this.opt && opt.random && opt.index === undefined)
 			opt.index = random(map.split(sequence).length);
 
 		if(this.opt && opt.index>0) {

exec/tdfiglet.js

@@ -12,8 +12,7 @@ opt = {
     justify: LEFT_JUSTIFY,
     width: DEFAULT_WIDTH,
     random: false,
-    info: false,
-    index: 0
+    info: false
 };
 
 // Function declarations (Synchronet JS style)