Maybe make this work better with mono...
Merge remote-tracking branch 'upstream/mono' into mono

Conflicts:
	libsodium-net/CryptoHash.cs
	libsodium-net/GenericHash.cs
	libsodium-net/OneTimeAuth.cs
	libsodium-net/PublicKeyAuth.cs
	libsodium-net/PublicKeyBox.cs
	libsodium-net/SecretBox.cs
	libsodium-net/SecretKeyAuth.cs
	libsodium-net/ShortHash.cs
	libsodium-net/SodiumCore.cs
	libsodium-net/StreamEncryption.cs