Use unsigned constants for all sizes
Merge branch 'master' of github.com:jedisct1/libsodium

* 'master' of github.com:jedisct1/libsodium:
  Use unsigned types for sizes in tests.
  Having dead code in the tree is sad, but keeps the diff with the reference implementation to a minimum.
  THANKS += @jshahbazi for the Fortran bindings