Make sure shaders are disabled as long as /sim/rendering/shaders/quality-level is 0 or non existing.

This should help those checking out models in fgviewer
To enable effects in fgviewer run it with:
fgviewer --prop /sim/rendering/shaders/quality-level -1
Also fix random buildings not showing up when model shader was set to 0 and generic was enabled.
Signed-off-by: Emilian Huminiuc <emilianh@gmail.com>

Effects/building.eff

@@ -342,7 +342,7 @@
   <technique n="11">
     <pass>
       <program n="0">
-        <vertex-shader n="0">Shaders/building-default.vert</vertex-shader>
+        <vertex-shader n="1">Shaders/building-default.vert</vertex-shader>
       </program>
     </pass>
   </technique>  

Effects/crop.eff

@@ -21,6 +21,7 @@
   <technique n="9">
     <predicate>
       <and>
+	    <property>/sim/rendering/shaders/quality-level</property>
         <property>/sim/rendering/shaders/crop</property>
 		<equal>
 			<value type="float">0.0</value>

Effects/flutter.eff

@@ -51,6 +51,7 @@
 	<technique n="9">
 		<predicate>
 			<and>
+				<property>/sim/rendering/shaders/quality-level</property>
 				<property>/sim/rendering/shaders/generic</property>
 				<or>
 					<less-equal>

Effects/forest.eff

@@ -69,7 +69,8 @@
   <technique n="9">
     <predicate>
       <and>
-        <property>/sim/rendering/shaders/transition</property>
+		<property>/sim/rendering/shaders/quality-level</property>
+		<property>/sim/rendering/shaders/transition</property>
 		<equal>
 			<value type="float">0.0</value>
 			<float-property>/sim/rendering/rembrandt/enabled</float-property>

Effects/glacier.eff

@@ -70,6 +70,7 @@
   <technique n="9">
     <predicate>
       <and>
+		<property>/sim/rendering/shaders/quality-level</property>
         <property>/sim/rendering/shaders/transition</property>
 		<equal>
 			<value type="float">0.0</value>

Effects/herbtundra.eff

@@ -70,6 +70,7 @@
   <technique n="9">
     <predicate>
       <and>
+		<property>/sim/rendering/shaders/quality-level</property>
         <property>/sim/rendering/shaders/transition</property>
 		<equal>
 			<value type="float">0.0</value>

Effects/landmass.eff

@@ -48,6 +48,7 @@
 	<technique n="8">
 		<predicate>
 			<and>
+				<property>/sim/rendering/shaders/quality-level</property>
 				<property>/sim/rendering/shaders/landmass</property>
 				<less-equal>
 					<value type="float">4.0</value>
@@ -375,6 +376,7 @@
 	<technique n="9">
 		<predicate>
 			<and>
+				<property>/sim/rendering/shaders/quality-level</property>
 				<property>/sim/rendering/shaders/landmass</property>
 				<equal>
 					<value type="float">0.0</value>

Effects/model-combined.eff

@@ -766,6 +766,7 @@ please see Docs/README.model-combined.eff for documentation
 	<technique n="9">
 	  <predicate>
 		<and>
+		  <property>/sim/rendering/shaders/quality-level</property>
 		  <property>/sim/rendering/shaders/model</property>
 		  <or>
 			<less-equal>

Effects/model-default.eff

@@ -207,6 +207,7 @@
 	<technique n="11">
 		<predicate>
 			<and>
+				<property>/sim/rendering/shaders/quality-level</property>
 				<property>/sim/rendering/shaders/generic</property>
 				<or>
 					<less-equal>

Effects/reflect-bump-spec.eff

@@ -135,6 +135,7 @@ EXAMPLES: You can find examples of both usages in the Hunter and Lightning model
 	<technique n="9">
 		<predicate>
 			<and>
+				<property>/sim/rendering/shaders/quality-level</property>
 				<property>/sim/rendering/shaders/model</property>
 				<or>
 					<less-equal>

Effects/reflect.eff

@@ -114,6 +114,7 @@
 
 		<predicate>
 			<and>
+				<property>/sim/rendering/shaders/quality-level</property>
 				<property>/sim/rendering/shaders/model</property>
 				<or>
 					<less-equal>

Effects/runway.eff

@@ -413,6 +413,7 @@
 	<technique n="9">
 		<predicate>
 			<and>
+				<property>/sim/rendering/shaders/quality-level</property>
 				<property>/sim/rendering/shaders/generic</property>
 				<or>
 					<less-equal>

Effects/terrain-default.eff

@@ -540,6 +540,7 @@
   <technique n="11">
     <predicate>
       <and>
+		<property>/sim/rendering/shaders/quality-level</property>
         <property>/sim/rendering/shaders/generic</property>
         <or>
           <less-equal>

Effects/transition.eff

@@ -388,6 +388,7 @@ parameters :
 	<technique n="9">
 		<predicate>
 			<and>
+				<property>/sim/rendering/shaders/quality-level</property>
 				<property>/sim/rendering/shaders/transition</property>
 				<equal>
 					<value type="float">0.0</value>

Effects/tree.eff

@@ -389,6 +389,7 @@
 	<technique n="10">
 		<predicate>
 			<and>
+				<property>/sim/rendering/shaders/quality-level</property>
 				<property>/sim/rendering/random-vegetation</property>
 				<less-equal>
 					<value type="float">1.0</value>

Effects/urban.eff

@@ -934,6 +934,7 @@
 	<technique n="8">
 		<predicate>
 			<and>
+				<property>/sim/rendering/shaders/quality-level</property>
 				<property>/sim/rendering/shaders/urban</property>
 				<less-equal>
 					<value type="float">4.0</value>
@@ -1183,6 +1184,7 @@
 	<technique n="9">
 		<predicate>
 			<and>
+				<property>/sim/rendering/shaders/quality-level</property>
 				<property>/sim/rendering/shaders/urban</property>
 				<less-equal>
 					<value type="float">1.0</value>

Effects/water.eff

@@ -1637,6 +1637,7 @@
 	<technique n="8">
 		<predicate>
 			<and>
+				<property>/sim/rendering/shaders/quality-level</property>
 				<property>/sim/rendering/shaders/water</property>
 				<less-equal>
 					<value type="float">4.0</value>
@@ -2010,6 +2011,7 @@
 	<technique n="9">
 		<predicate>
 			<and>
+				<property>/sim/rendering/shaders/quality-level</property>
 				<property>/sim/rendering/shaders/water</property>
 				<less-equal>
 					<value type="float">2.0</value>

Nasal/gui.nas

@@ -1435,7 +1435,9 @@ var update_shader_settings = func() {
         setprop("/sim/rendering/shaders/crop",qualityLvl);
         setprop("/sim/rendering/shaders/generic",qualityLvl);
         setprop("/sim/rendering/shaders/transition",qualityLvl);
-    }
+    } else {
+		setprop("/sim/rendering/shaders/quality-level",-1);
+	}
 
     if (rembrandtOn) {
 		setprop("/sim/rendering/shaders/skydome",0);