Fix Issue #4611 by using {{unescapedDescription}} (#4641)

* Use {{unescapedDescription}} in html, html2

This addresses https://github.com/swagger-api/swagger-codegen/issues/4611
Replace {{description}} with {{unescapedDescription}}

This is an improvement but because of issue #1203 and/or #3436 (fix not
yet impleented), Markdown is not being processed and converted to HTML.

* Add generated petstore samples index.html

* Copy unescapedDescription

modules/swagger-codegen/src/main/java/io/swagger/codegen/CodegenParameter.java

@@ -90,6 +90,7 @@ public class CodegenParameter {
         output.collectionFormat = this.collectionFormat;
         output.isCollectionFormatMulti = this.isCollectionFormatMulti;
         output.description = this.description;
+        output.unescapedDescription = this.unescapedDescription;
         output.baseType = this.baseType;
         output.isFormParam = this.isFormParam;
         output.isQueryParam = this.isQueryParam;

modules/swagger-codegen/src/main/java/io/swagger/codegen/CodegenProperty.java

@@ -11,6 +11,7 @@ public class CodegenProperty implements Cloneable {
           datatypeWithEnum, dataFormat, name, min, max, defaultValue, defaultValueWithParam,
           baseType, containerType, title;
 
+    /** The 'description' string without escape charcters needed by some programming languages/targets */
     public String unescapedDescription;
 
     /**
@@ -323,6 +324,6 @@ public class CodegenProperty implements Cloneable {
             throw new IllegalStateException(e);
         }
     }
-    
-    
+
+
 }