Move distortion correction, motion correction and registration data to MRIAcquisition (see comment in #43)

Rename acquisitionDuration to volumeAcquisitionTime because this is should not be confused with the length of the time series but refers to the time required to acquire all slices that make up one 3D brain volume. In a lot of fMRI settings this time is equal to TR (where one TR = one full volume), only in advanced fMRI cases the TR might be larger or smaller (depending on the case).

we should rename the activity dynamicMRIAcquisition which would include besides functional MRI also physiological MRI techniques since all of them seem to use the same parameter types and only different parameter values and constraints. So they can be handled by one activity schema.

following this you could also rename the activity MRIAcquisition to staticMRIAcquisition (covering then standard structural MRI and diffusion MRIs)