WIP refactoring utils/ported.hpp for Armadillo
WIP fixup test_utils_ported
WIP removed deprecated for linspace and hist
WIP callbacks armadillo
WIP extract armadillo
WIP descriptors armadillo
WIP vocabulary armadillo
WIP index armadillo
WIP fixup utils/data
WIP test_descriptors
WIP fixup callbacks with curiously recursive pattern