[T] RM; Add observation point output.

Using geometry input but multiple meshes output feature.

Tests/Data/RichardsMechanics/RichardsFlow_2d_small.prj

@@ -118,6 +118,10 @@
         <output>
             <type>VTK</type>
             <prefix>RichardsFlow_2d_small</prefix>
+            <meshes>
+                <mesh>Richards_2d</mesh>
+                <mesh>Richards_2d_geometry_OBSERVATION_POINT</mesh>
+            </meshes>
             <timesteps>
                 <pair>
                     <repeat>9</repeat>

Tests/Data/RichardsMechanics/Richards_2d.gml

 version https://git-lfs.github.com/spec/v1
-oid sha256:f2d720461be8d6f72f0d2b2bf5b48152b8860dcabdd812331251fa3059ddfc4e
-size 963
+oid sha256:1f635aabe80a0ca1af8a8ad10718ba5d3af0b6edfe00275eea1717a1b3a91cd1
+size 1030