BUG: in NthElementAdaptor pass by reference to modify argument

Change-Id: I54d9b264216857ebd3b2ba7ac6d302e9ebdd56f8
Merge topic 'FixVectorImageGradientRecursiveGaussianRVO'

941f550 BUG: in NthElementAdaptor pass by reference to modify argument
BUG: LabelGeometry matrix difference tolerance

This patch relaxes the tolerance used to compare matrices so that the
tests will pass on very different OS versions.  It also corrects a
minor bug of default values causing compiler errors on some OS
versions.

Change-Id: I0866ec3597e7abafb418f3329a00bac8ca6be371
Merge topic 'LabelGeometryTolerance'

c3a6fb4 BUG: LabelGeometry matrix difference tolerance
ENH: Added progress reporting to Masked FFT NCC

Added progress reporting to the
itkMaskedFFTNormalizedCorrelationImageFilter. The progress reporting
is calculated based on the progress of the FFT and IFFT computations,
which are the most computationally expensive steps of the algorithm.
There are 12 FFT/IFFT computations in the algorithm.

This patch address JIRA ticket: ITK-3099

Change-Id: Icd6af337f15ae359ec5bf1ab5fe84200a0575ff2
Merge topic 'MaskedFFTProgressReporting'

f471f3d ENH: Added progress reporting to Masked FFT NCC