MRIaggr-filtrage2D_cpp: 2D filtering
In bozenne/MRIaggr: Management, Display, and Processing of Medical Imaging Data

C++ function call by calcFilter that performs two dimensional filtering. For internal use.

1	filtrage2D_cpp(M_data, M_operateur, index_data, bilateral, na_rm)

`M_data`	matrix to which the filter will be applied.
`M_operateur`	the filter to be applied.
`index_data`	index of the non NA data.
`bilateral`	should the influence of each neighbor be ponderated by the difference in signal with the considered observation ?
`na_rm`	should the observations with missing values in their neighbourhood be removed ? Otherwise the ponderation is adjusted.