Improved US visualisation

[jpdefrutos]

It is common to use the US raw images directly from the scanner for AI dev. These images lack most of the post-processing filtering done by manufacturers, looking quite different from what anntoators are used to.

It would be convenient to be able to either display the raw and post-processed US slides in a side-by-side configuration. Or perhaps add some intensity, contrasts, and gamma curves settings for the anntotators to work with