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/server/petstore/php-slim/lib/Model/Dog.php

@@ -10,12 +10,12 @@ namespace OpenAPIServer\Model;
 class Dog
 {
     
-    /** @var string $breed */
-    private $breed;
-    
     /** @var string $className */
     private $className;
     
     /** @var string $color */
     private $color;
+    
+    /** @var string $breed */
+    private $breed;
 }