The initial cut-in was missing preamble present in Moon's curve25519_donna function. It originally tested good because we only perform a pairwise consistency check in release builds. Comprehensive testing with debug builds revealed the problem. Debug builds cross-validate against Bernstein's TweetNaCl library.
Add is_clamped for secret key validation.
Cleanup paramter names in Donna::curve25519 to follow function.
Overload Donna::curve25519 to implicitly use base point if not provided.
Add additional asserts to let the code debug itself.
Update documentation.
