Add ability to add custom shaders to ColorProcessorJobs

app/shaders/chromakey.frag

@@ -0,0 +1,34 @@
+uniform sampler2D tex_in;
+in vec2 ove_texcoord;
+out vec4 frag_color;
+
+// OCIO shader code
+%1
+
+// Assume D65 white point
+float Xn = 95.0489;
+float Yn = 100.0;
+float Zn = 108.8840;
+float delta = 0.20689655172; // 6/29
+
+float func(float t) {
+  if (t > pow(delta, 3.0)){
+    return pow(t, 1.0/3.0);
+  } else{
+    return (t / (3.0 * pow(delta, 2))) + 4.0/29.0;
+  }
+}
+
+void main() {
+  vec4 col = texture2D(tex_in, ove_texcoord);
+  vec4 new_col;
+
+  new_col = %2(col);
+
+  vec4 lab;
+  lab.r = 116.0 * func(col.g / Yn) - 16.0;
+  lab.g = 500.0 * (func(col.r / Xn) -  func(col.g / Yn));
+  lab.b = 200.0 * (func(col.g / Yn) -  func(col.b / Zn));
+  lab.w = 1.0;
+  frag_color = col;
+}