Add mask option to rtkfieldofview
Add DPExtractShroudSignalImageFilter

- New filter to extract shroud signal from a shroud image using dynamic
programming.
Add Reg1DExtractShroudSignalImageFilter

- New filter to extract shroud signal from a shroud image using 1D
registrations.
Add rtkextractshroudsignal

- New application to extract shroud signal from a shroud image.