Fix memory management of opencv bridge.
Fix boxNd nrows and ncols.
Add box filling.
Improve imageNd:
  Fix data alignement with alignof.
  Add subimage construction.
  Refactor and fix memory management of external buffers.
Add plus_promotion and cast.
Add border to pyramid levels, make subsample2 generic.
Add sum
Test cast.
Test tuple_utils.
Add block_wise.
Update vpp.hh
Add apply_args_transform.
Complete opencv_bridge test.
Subimage construction with operator|
Test subimage
Compilation of tests.
Continue to build the pyrlk example
Add constructor to keypoint class
Add blockwise_maxima selection.