Optimizing calls to Reslicing function that follows 4D to 3D registration and the reslicing take major part of total processing time.

Fixing defect:  After successfully registering the whole 4D PET to MPRAGE, attempted to do "Dynamic Averaging" function of first 100 PET timepoints.  Result is incorrect and is being investigated.

Several registration scenarios had uninitialize parameters, f.e.  Fine Interpolation was not initialize in most

of the registration scenarios.  Corrected.

PET to MPRAGE registration:  There is a strange defect that PET with dozen or so timeframes is registered fine to MPRAGE. But when I try to register 100+ timepoints, registration runs in reasonable time, but the outputs entirely empty result.

Highly parallelized Volume cropping function (UI-level), so it runs much faster now.