made gl3 UBOs optional; also tried other snake oil

src/gl/shaders/header.frag

@@ -0,0 +1,28 @@
+#ifdef USE_UBOS
+layout(std140) uniform State
+{
+	vec2 u_alphaRef;
+
+	float u_fogStart;
+	float u_fogEnd;
+	float u_fogRange;
+	float u_fogDisable;
+	vec4  u_fogColor;
+};
+#else
+//uniform int   u_alphaTest;
+//uniform float u_alphaRef;
+uniform vec2 u_alphaRef;
+
+uniform float u_fogStart;
+uniform float u_fogEnd;
+uniform float u_fogRange;
+uniform float u_fogDisable;
+uniform vec4  u_fogColor;
+#endif
+
+void DoAlphaTest(float a)
+{
+	if(a < u_alphaRef.x || a >= u_alphaRef.y)
+		discard;
+}