Implement Bitmap 'blur'

I was a bit confused at first because I thought Enterbrain
had actually implemented a full Gaussian blur, but nope,
just dumb averaging.

shader/blurV.vert

@@ -0,0 +1,19 @@
+
+uniform mat4 projMat;
+
+uniform vec2 texSizeInv;
+
+attribute vec2 position;
+attribute vec2 texCoord;
+
+varying vec2 v_texCoord;
+varying vec2 v_blurCoord[2];
+
+void main()
+{
+	gl_Position = projMat * vec4(position, 0, 1);
+
+	v_texCoord = texCoord * texSizeInv;
+	v_blurCoord[0] = vec2(texCoord.x, texCoord.y-1) * texSizeInv;
+	v_blurCoord[1] = vec2(texCoord.x, texCoord.y+1) * texSizeInv;
+}