fixes to go with the gpuloop PR in httomo

[dkazanc]

To be merged only with gpuloop branch in httomo as removing of decorators will break httomo main

• removes decorators from httomolibgpu
• removes fresnel filter (can be added later)
• rescale_to_int function added
• removes distortion correction (Savu) (can be added later)
• adds data_scaler method for down/up sampling
• adds circular masking in reconstruction
• various bug fixes

[dkazanc]

TODO: FBP needs to have cutoff frequency parameter when changes from fourier branch are in main in ToMoBAR.