Move the cffi defintions into nacl.c._lib
Starting add the crypto_box_* functions
Fix prebuilding extension modules
Port the crypto_box* functionality to use the new layout
Move the random implementation over to the new layout
Port the crypto_secretbox implementation to the new layout
Refactor the signing support to the new layout
Move the hash functions over to the new layout
Fix packaging
Ensure there is no implicit compilation again
Merge pull request #42 from dstufft/refactor-c-api

Refactor the C API