In ForwardDepth renderpath, clear depth two times as on OpenGL it can't be guaranteed that the proper rendering pass depth buffer is same as in the linear depth pass. Closes #1073.

bin/CoreData/RenderPaths/ForwardDepth.xml

@@ -2,7 +2,7 @@
     <rendertarget name="depth" sizedivisor="1 1" format="lineardepth" />
     <command type="clear" color="1 1 1 1" depth="1.0" stencil="0" output="depth" />
     <command type="scenepass" pass="depth" output="depth" />
-    <command type="clear" color="fog" />
+    <command type="clear" color="fog" depth="1.0" />
     <command type="scenepass" pass="base" vertexlights="true" metadata="base" />
     <command type="forwardlights" pass="light" />
     <command type="scenepass" pass="postopaque" />