Handle pedestal in PES and use GPU if available in BNN
- Before this MR, if there was a non-zero constant level in the PES data, at the region-of-interest discovery step, there would be an edge effect due to the smoothening, which causes a large peak at the origin. This large peak at the origin would be seen as clear evidence of a region-of-interest. This can be avoided by subtracting the zero-level from the PES. It has been observed in run 185 of proposal 6176, although it is not clear why this pedestal is there! The PES should not be providing data in this format. @schmidtp
- The BNN method is quite slow without the GPU. Use it if it is available.