Allow more than 1 activation state per actuator, but only for dyntype user.

Fixes #305.

PiperOrigin-RevId: 486597273
Change-Id: I0b5913622c1d2e8297427d4ffe34cf8bfd70ec5e

Author: yuvaltassa

dm_control/mjcf/schema.xml

@@ -383,6 +383,7 @@
         <element name="general">
           <attributes>
             <attribute name="group" type="int"/>
+            <attribute name="actdim" type="int"/>
             <attribute name="ctrllimited" type="keyword" valid_values="false true auto"/>
             <attribute name="forcelimited" type="keyword" valid_values="false true auto"/>
             <attribute name="ctrlrange" type="array" array_type="float" array_size="2"/>
@@ -685,6 +686,7 @@
                 <attribute name="gear" type="array" array_type="float" array_size="6"/>
                 <attribute name="cranklength" type="float"/>
                 <attribute name="user" type="array" array_type="float"/>
+                <attribute name="actdim" type="int"/>
                 <attribute name="dyntype" type="keyword" valid_values="none integrator filter user"/>
                 <attribute name="gaintype" type="keyword" valid_values="fixed affine user"/>
                 <attribute name="biastype" type="keyword" valid_values="none affine user"/>
@@ -1546,6 +1548,7 @@
             <attribute name="name" type="identifier"/>
             <attribute name="class" type="reference" reference_namespace="default"/>
             <attribute name="group" type="int"/>
+            <attribute name="actdim" type="int"/>
             <attribute name="ctrllimited" type="keyword" valid_values="false true auto"/>
             <attribute name="forcelimited" type="keyword" valid_values="false true auto"/>
             <attribute name="actlimited" type="keyword" valid_values="false true auto"/>