Refuse to work on floating point images

No type of sensor that is known to us is producing floating point quantized
images, so this usually means some kind of pre-processing has happened
(deconvolution?). In such a situation evaluating the SNR doesn't make sense any
more since the pre-processing will have a strong impact on the results.

src/main/resources/scripts/Plugins/NoiSee/NoiSee_Bead_Analysis.ijm

@@ -541,6 +541,11 @@ function process_beads() {
     File.makeDirectory(respath);
     // TODO: check if image dimensions meet our expectations (z=1, t>1)
 
+    if (bitDepth() == 32) {
+        print("Floating point images are not supported!");
+        exit_show();
+    }
+
     print("processing image: " + fname + "  (location: [" + fpath + "])");
     if (bitDepth() > 8) {
         print("image type " +  bitDepth() + " bit detected, converting to 8 bit...");