Curring for set/configure/enable/disable

lib/index.js

@@ -68,6 +68,7 @@ function MarkdownIt(presetName, options) {
 //
 MarkdownIt.prototype.set = function (options) {
   assign(this.options, options);
+  return this;
 };
 
 
@@ -87,6 +88,7 @@ MarkdownIt.prototype.configure = function (presets) {
       }
     });
   }
+  return this;
 };
 
 
@@ -96,6 +98,7 @@ MarkdownIt.prototype.enable = function (list) {
   [ 'core', 'block', 'inline' ].forEach(function (chain) {
     this[chain].ruler.enable(list, true);
   }, this);
+  return this;
 };
 
 
@@ -105,6 +108,7 @@ MarkdownIt.prototype.disable = function (list) {
   [ 'core', 'block', 'inline' ].forEach(function (chain) {
     this[chain].ruler.disable(list, true);
   }, this);
+  return this;
 };