Avoid duplication of fullscreen vertex shader

Effects/ambient.eff

@@ -40,7 +40,7 @@
 				<name>ao-3</name>
 			</texture-unit>
 			<program>
-				<vertex-shader>Shaders/ambient.vert</vertex-shader>
+				<vertex-shader>Shaders/fullscreen.vert</vertex-shader>
 				<fragment-shader>Shaders/ambient.frag</fragment-shader>
 			</program>
 			<uniform>

Effects/blur.eff

@@ -14,7 +14,7 @@
 				<name><use>buffer-name</use></name>
 			</texture-unit>
 			<program>
-				<vertex-shader>Shaders/blur.vert</vertex-shader>
+				<vertex-shader>Shaders/fullscreen.vert</vertex-shader>
 				<fragment-shader>Shaders/blur.frag</fragment-shader>
 			</program>
 			<uniform>

Effects/display.eff

@@ -43,7 +43,7 @@
 				<name>ao-3</name>
 			</texture-unit>
 			<program>
-				<vertex-shader>Shaders/display.vert</vertex-shader>
+				<vertex-shader>Shaders/fullscreen.vert</vertex-shader>
 				<fragment-shader>Shaders/display.frag</fragment-shader>
 			</program>
 			<uniform>

Shaders/blur.vert

@@ -1,4 +0,0 @@
-void main() {
-    gl_Position = gl_Vertex;
-    gl_TexCoord[0] = gl_MultiTexCoord0;
-}

Shaders/display.vert

@@ -1,4 +0,0 @@
-void main() {
-    gl_Position = gl_Vertex;
-    gl_TexCoord[0] = gl_MultiTexCoord0;
-}