Renew B-Value list after DICOM loading
Allow selecting dwi image in PointBasedRegistration

* checked two-fold: one by searching an 'Image' substring in the class
* name ( does not break the old condition )

* second by verifying the result of a dynamic_cast<Image>
Merge branch 'bug-13943-BValue-update-after-dicom-loading'
Merge branch 'bug-14043-Registration-on-dwis'