Merge
[NEW] Add base class to simulate PSF
[NEW] Add Gaussian PSF
[NEW] Add BoxCar PSF
[TEST] Add a test for PSF kernels
[NEW] New filter to compute H Matrix in super-Resolution pipeline
[NEW] Cost function is computed separately for Super-Resolution pipeline
[NEW] Add a Wrapper in order to use SR cost function with VNL optimizers
[NEW] Add Wrapper in order to use SR Cost Function with ITK optimizers
[IMP] Update SuperResolutionFilter, remove old code, add new filters
[CLEAN] SuperResolutionFilterTest is now cleaned ! But still unstable !
Merge branch 'experimental'