Project does not build against latest libsodium 0.7.0 release

[iparq]

Some headers have changed, some removed, some added. Bit rot and all that. I have tweaked my version of the project, but also the libsodium.sh doesn't leave any libs in the libsodium_dst directory (although it does put the headers there). It would be great if - as part of the docs - you specified with which version of libsodium you are compatible.