added rendering of MOCV vertex colours

shaders/wmo.vert

@@ -2,8 +2,10 @@
 layout(location = 0) in vec3 vertex_position; // position
 layout(location = 1) in vec3 vertex_normal; // colour of each vertex point
 layout(location = 2) in vec2 vertex_tex;
+layout(location = 3) in vec4 vertex_colour;
 
 out vec2 TexCoord;
+out vec4 VertexColour;
 
 uniform mat4 matrix; // must match "matrix" in C code
 uniform mat4 view;   // must match "view" in C code
@@ -12,4 +14,5 @@ uniform mat4 proj;   // must match "proj" in C code
 void main() {
     gl_Position = proj * view * matrix * vec4(vertex_position, 1.0);
     TexCoord = vertex_tex;
+    VertexColour = vertex_colour;
 }