Film negative processing: first usable version. Only supports bayer raw files, thumbnails don't work

Added performance improvements suggested by heckflosse. Lowered median sampling step from 7 to 5 since calculation is now much faster.

Added support for Fuji X-Trans raw files.

Applied SSE2 patch provided by @heckflosse, improves performance in main processing loop.

Moved film negative processing stuff in its own compilation unit.

Code cleanup: removed redundant omp directives.

Added check for dead pixels, going above threshold after inversion. ST_BAYER only for now.

Reverted leftover hack in cropwindow.cc

rtengine/simpleprocess.cc

@@ -209,6 +209,11 @@ private:
         imgsrc->setCurrentFrame (params.raw.bayersensor.imageNum);
         imgsrc->preprocess ( params.raw, params.lensProf, params.coarse, params.dirpyrDenoise.enabled);
 
+        // After preprocess, run film negative processing if enabled
+        if(imgsrc->getSensorType() == ST_BAYER && params.filmNegative.enabled) {
+            imgsrc->filmNegativeProcess (params.filmNegative);
+        }
+
         if (pl) {
             pl->setProgress (0.20);
         }