allow contract reference & attribute refer to another

Author: SmartLayer

schema/data.xsd

@@ -146,7 +146,7 @@
                                 </xs:complexType>
                             </xs:element>
                         </xs:sequence>
-                        <xs:attribute name="key" use="required" type="xs:integer"/>
+                        <xs:attribute name="key" use="required" type="xs:string"/>
                     </xs:complexType>
                 </xs:element>
             </xs:sequence>

schema/tokenscript.xsd

@@ -303,6 +303,15 @@
                 <element ref="ethereum:call"/>
                 <element ref="ts:user-entry"/>
                 <element ref="ts:token-id"/>
+                <element ref="ts:data"/>
+                <element name="attribute">
+                    <complexType>
+                        <sequence>
+                            <element minOccurs="0" ref="ts:mapping"/>
+                        </sequence>
+                        <attribute name="ref" type="NCName"/>
+                    </complexType>
+                </element>
             </choice>
         </complexType>
     </element>