Add crypto_box_seed_keypair like crypto_sign_seed_keypair

Uses sk = seed.
Test crypto_box_seed_keypair
Merge pull request #161 from jvarho/crypto-box-seed-keypair

Add crypto_box_seed_keypair
Change crypto_box_seed_keypair to use SHA-512 of the seed

This makes it compatible with what js-nacl and racl do.
Mention crypto_box_seed_keypair
Avoid redefinition of be32enc() on NetBSD.
aes128ctr: use an union to avoid breaking aliasing rules.
Add extra braces for int128 initializers
Remove useless #include
Add test for Tarsnap testvectors to low-level scrypt interface
Fix Travis g++ errors
To comply with C89:
 - Moved variable declarations to top of function
 - Constant output buffer inside the function

Moved strlen calls from main to inside function to make code easier to read.

Also switched from fancy quotes to single quotes in expected output
Change spaces to tab in Makefile.am after pwhash_scrypt_ll addition
Merge pull request #167 from truenull/master

Tarsnap test vectors tested on Windows
Make arguments match the format string in test/default/pwhash_scrypt_ll.c ...
More test/default/pwhash_scrypt_ll.c fixes
Indent
Do not suggest running anything but `make install` with root privileges.
Revert "Make curve25519-donna-c64 handle non-canonical points like the ref implementation."

This reverts commit bd8cbd3175cd2041945ea28bf0d4521fa79de26b.

Conflicts:
	src/libsodium/crypto_scalarmult/curve25519/donna_c64/smult_curve25519_donna_c64.c
	test/default/scalarmult7.c
	test/default/scalarmult8.c
Revert bd8cbd3175cd2041945ea28bf0d4521fa79de26b
Go back to masking the high bit in curve25519 instead of processing the
key as a 256-bit value.