Add texture and material definition for casing on 3d Taxiway signs.

Signed-off-by: Emilian Huminiuc <emilianh@gmail.com>

Materials/base/materials-base.xml

@@ -575,4 +575,26 @@ Shared parameters for various materials.
   <load-resistance>1e10</load-resistance>
 </material>
 
+<!-- Taxiway signs -->
+    <material n="2100">
+        <name>signcase</name>
+        <texture>Signs/signs_case.png</texture>
+        <effect>Effects/terrain-default</effect>
+        <ambient>
+            <r>1.0</r>
+            <g>1.0</g>
+            <b>1.0</b>
+        </ambient>
+        <glyph>
+            <name>cover1</name>
+            <left>0.000</left>
+            <right>0.625</right>
+        </glyph>
+        <glyph>
+            <name>cover2</name>
+            <left>0.625</left>
+            <right>0.000</right>
+        </glyph>
+    </material>
+
 </PropertyList>