Rust native binding to libsodium
```toml
[dependencies] libsodium-ffi = "0.1" ```
Environement variables
SODIUM_LIB_DIR=/path/to/libsodium
for telling cargo where to find libsodium
SODIUM_STATIC=yes
for telling cargo to static-link libsodium
SODIUM_BUILD_STATIC=yes
force build from source instead of trying to find libsodium in system-wide