Detect failure to load image.
Also compute gradient magnitude and orientation feats.
Fixed a linking error.
Cov/corr computation and first "unit"tests.
Distance computation+tests.
Added geodesig distance
Expose computation of corr of a region.
Fixed the array's grid size from 8 to 16
Fixed bug in eig_fn
Slight improvement of mkspd using completeSymm
Put to_s into warco namespace
Switched to relative tolerance for tests.
Better handling of random seed in testing.