added mosaic filter node

app/shaders/mosaic.frag

@@ -0,0 +1,38 @@
+#version 150
+
+#ifdef GL_ES
+precision highp int;
+precision highp float;
+#endif
+
+// Input texture
+uniform sampler2D tex_in;
+
+uniform float horiz_in;
+uniform float vert_in;
+
+// Input texture coordinate
+in vec2 ove_texcoord;
+
+// Output color
+out vec4 fragColor;
+
+void main() {
+  float x;
+  float y;
+
+  if (horiz_in > 0.0) {
+    x = floor(ove_texcoord.x * horiz_in) / horiz_in;
+  } else {
+    x = ove_texcoord.x;
+  }
+
+  if (vert_in > 0.0) {
+    y = floor(ove_texcoord.y * vert_in) / vert_in;
+  } else {
+    y = ove_texcoord.y;
+  }
+
+  vec4 color = texture(tex_in, vec2(x, y));
+  fragColor = color;
+}