Add option to unwrap I/O block aggregates in reflection

* We follow similar rules to uniform block exploding.

Test/reflection.options.geom

@@ -0,0 +1,31 @@
+#version 330 core
+
+precision highp float;
+
+layout(triangles) in;
+layout(triangle_strip, max_vertices = 4) out;
+
+in block
+{
+    vec2 Color;
+    vec2 Texcoord;
+    flat ivec3 in_a;
+} In[];
+
+out block
+{
+    vec4 Color;
+    vec4 a;
+    vec2 b[3];
+} Out;
+
+void main()
+{
+    for(int i = 0; i < gl_in.length(); ++i)
+    {
+        gl_Position = gl_in[i].gl_Position;
+        Out.Color = vec4(In[i].Color, 0, 1);
+        EmitVertex();
+    }
+    EndPrimitive();
+}