Cast shadows of the cab lamp from the cab in the GL 4.6 renderer

shaders/shadowcube.vert

@@ -0,0 +1,15 @@
+layout(location = 0) in vec3 v_vert;
+layout(location = 2) in vec2 v_coord;
+
+// position in the space of the cube shadow map being drawn (origin at the lamp), see shadowcube.geom
+out vec3 g_pos;
+out vec2 g_coord;
+
+#include <common>
+
+void main()
+{
+	g_pos = (effective_modelview() * vec4(v_vert, 1.0f)).xyz;
+	g_coord = v_coord;
+	gl_Position = vec4(g_pos, 1.0f);
+}