fix(extension-registering) removeExtension implementation

Author: dennisss

src/converter.js

@@ -532,12 +532,12 @@ showdown.Converter = function (converterOptions) {
       var ext = extension[a];
       for (var i = 0; i < langExtensions.length; ++i) {
         if (langExtensions[i] === ext) {
-          langExtensions[i].splice(i, 1);
+          langExtensions.splice(i, 1);
         }
       }
-      for (var ii = 0; ii < outputModifiers.length; ++i) {
+      for (var ii = 0; ii < outputModifiers.length; ++ii) {
         if (outputModifiers[ii] === ext) {
-          outputModifiers[ii].splice(i, 1);
+          outputModifiers.splice(ii, 1);
         }
       }
     }

test/node/showdown.Converter.js

@@ -143,6 +143,14 @@ describe('showdown.Converter', function () {
       converter.getAllExtensions().language.should.contain(extObjMock);
       showdown.resetExtensions();
     });
+
+    it('removeExtension() should remove an added extension', function () {
+      var converter = new showdown.Converter();
+      converter.addExtension(extObjMock);
+
+      converter.removeExtension(extObjMock);
+      converter.getAllExtensions().language.should.not.contain(extObjMock);
+    });
   });
 
   describe('events', function () {