Add support for multiple inheritance (#1664)

* add all parent names

* clean up supportsInheritance

* fix npe

* fix allVars, fix test cases

* add more tests, remove comments

* update docker m2 cache dir, add more tests, fix mandatory

* update samples

* regenerate js spec files

* add logic to detect self reference

* add isSelfReference flag to codegen property

* add ruby tests for cat model

* remove debugging info

* fix JS allvars not have x-js-doctype

* update samples

* update js samples

samples/client/petstore/javascript-es6/src/model/Cat.js

@@ -25,7 +25,7 @@ class Cat {
      * @alias module:model/Cat
      * @extends module:model/Animal
      * @implements module:model/Animal
-     * @param className {} 
+     * @param className {String} 
      */
     constructor(className) { 
         Animal.initialize(this, className);

samples/client/petstore/javascript-es6/src/model/Dog.js

@@ -25,7 +25,7 @@ class Dog {
      * @alias module:model/Dog
      * @extends module:model/Animal
      * @implements module:model/Animal
-     * @param className {} 
+     * @param className {String} 
      */
     constructor(className) { 
         Animal.initialize(this, className);