Fix shadercode

Projekte/mdga/client/src/main/resources/MatDefs/SelectObjectOutliner/Post15.vert

@@ -1,8 +1,10 @@
-// Use 'in' for vertex attributes
+#version 150
+
+// Vertex attributes
 in vec4 inPosition;
 in vec2 inTexCoord;
 
-// Use 'out' for passing data to the fragment shader
+// Output to fragment shader
 out vec2 texCoord;
 
 void main() {