JPEG Lossless transformation: add an option to NOT optimize + warn users that optimizations are lossless

[esv]

Observing that your file shrinks on lossless transformations is unexpected and can confuse users, who think that they've lost something even if the reduction in size is a result of lossless optimizations
I suggest to implement the following three items to avoid this confusion:

1. Add an extra option to disable any optimizations. There already exists a similar one "Settings→Formats→Write→JPEG→Optimize Huffman table", maybe add the same option in the same place, but name it "Optimize Huffman table during lossless transformations (reduces file size without any loss of quality)"
2. Show an extra info message when you invoke the lossless transformation (which you can disable just like the warning about block sizes during the lossless crop), something like:
   "
   Lossless transformations can lead to a reduction in file size, but still without any loss in quality.
   You can verify it by losslessly rotating an image 4 times, copying it, rotating it 4 more times and noting that it's identical to the first copy.
   You can disable this in "Settings→Formats→Write→JPEG→Optimize Huffman table during lossless transformations", then even the first image rotated 4 times will be bit-for-bit identical to the original
   "
3. Retain the Progressive encoding type during lossless transform (so progressive images should not be converted to non-progressive)

This is a feature suggestion based on some older discussions, but posted under the proper forum section
viewtopic.php?f=82&t=38334
viewtopic.php?p=131357#p131357