Add macro to generate 16-bit test images

scripts/gen_16bit_testimage.ijm

+// macro to generate a 1D image containing pixel values ranging
+// from zero to the maximum possible value of the numbers given
+// in the bit_depth array - for every bit depth specified there
+// two pixels are added, one being (max - 1) and the second
+// being the max value itself
+
+bit_depths = newArray(0, 8, 9, 10, 11, 12, 14, 16);
+
+
+range = newArray(lengthOf(bit_depths) * 2);
+for (i = 0; i < lengthOf(bit_depths); i++) {
+	range[i*2] = pow(2, bit_depths[i]) - 2;
+	range[i*2+1] = pow(2, bit_depths[i]) - 1;
+}
+range[0] = 0;
+
+Array.print(range);
+
+title = "" + bit_depths[lengthOf(bit_depths)-1] + " bit test image";
+
+newImage(title, "16 bit", lengthOf(range) - 1, 1, 1);
+for (i = 1; i < lengthOf(range); i++) {
+	setPixel(i-1, 0, range[i]);	
+}
+run("Set... ", "zoom=3200");
+run("glasbey_on_dark");