export contact friction/damping through URDF and API

convert from contact friction/damping to cfm/erp
btCollisionObject::setContactFrictionAndDamping

data/cube_no_friction.urdf

@@ -4,8 +4,8 @@
     <contact>
       <lateral_friction value="0.0"/>
       <rolling_friction value="0.0"/>
-      <contact_cfm value="0.0"/>
-      <contact_erp value="1.0"/>
+      <stiffness value="300.0"/>
+      <damping value="10.0"/>
     </contact>
     <inertial>
       <origin rpy="0 0 0" xyz="0 0 0"/>

data/cube_small.urdf

@@ -3,10 +3,8 @@
   <link name="baseLink">
     <contact>
       <lateral_friction value="1.0"/>
-      <rolling_friction value="0.3"/>
+      <rolling_friction value="0.01"/>
       <inertia_scaling value="3.0"/>
-      <contact_cfm value="0.0"/>
-      <contact_erp value="1.0"/>
     </contact>
     <inertial>
       <origin rpy="0 0 0" xyz="0 0 0"/>

data/cube_soft.urdf

@@ -0,0 +1,32 @@
+<?xml version="0.0" ?>
+<robot name="cube.urdf">
+  <link name="baseLink">
+    <contact>
+      <lateral_friction value="1.0"/>
+      <rolling_friction value="0.0"/>
+      <stiffness value="300"/>
+      <damping value="10"/>
+    </contact>
+    <inertial>
+      <origin rpy="0 0 0" xyz="0 0 0"/>
+       <mass value="1.0"/>
+       <inertia ixx="1" ixy="0" ixz="0" iyy="1" iyz="0" izz="1"/>
+    </inertial>
+    <visual>
+      <origin rpy="0 0 0" xyz="0 0 0"/>
+      <geometry>
+				<mesh filename="cube.obj" scale="1 1 1"/>
+      </geometry>
+       <material name="white">
+        <color rgba="1 1 1 1"/>
+      </material>
+    </visual>
+    <collision>
+      <origin rpy="0 0 0" xyz="0 0 0"/>
+      <geometry>
+	 	<box size="1 1 1"/>
+      </geometry>
+    </collision>
+  </link>
+</robot>
+