Unlike what we had assumed, the "resetMinAndMax()" command doesn't set the
display range to min and max of the current bit depth but rather to the min and
max from the actual values. This was causing a high offset (many pixels with
value zero) after converting to 8 bit, so we rather calculate the display range
now from the actual values before converting to 8-bit.

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.

The logging related options are useful for development, but not relevant
for the end user. Hence they are now hard-coded in the macro instead of
presented in the dialog.

If required, anyone can open the macro code from the package by hitting the
"Source" button in the search results and adjust the corresponding lines.

This way we can at least show a message to the user when running in interactive
mode about closing any open images.