add deprecation warning for sanitize option

lib/marked.js

@@ -1536,6 +1536,12 @@ function findClosingBracket(str, b) {
   return -1;
 }
 
+function checkSanitizeDeprecation(opt) {
+  if (opt && opt.sanitize && !opt.silent) {
+    console.warn("marked(): sanitize and sanitizer parameters are deprecated since version 0.6.3 and will be removed from the next major version. Please use an external library, e.g. DOMPurify for your sanitization needs.");
+  }
+}
+
 /**
  * Marked
  */
@@ -1557,6 +1563,7 @@ function marked(src, opt, callback) {
     }
 
     opt = merge({}, marked.defaults, opt || {});
+    checkSanitizeDeprecation(opt);
 
     var highlight = opt.highlight,
         tokens,
@@ -1621,6 +1628,7 @@ function marked(src, opt, callback) {
   }
   try {
     if (opt) opt = merge({}, marked.defaults, opt);
+    checkSanitizeDeprecation(opt);
     return Parser.parse(Lexer.lex(src, opt), opt);
   } catch (e) {
     e.message += '\nPlease report this to https://github.com/markedjs/marked.';