As discussed in #694, vim encryption uses old,
obsolete algorithms that are poorly implemented.
Since insecure cryptography is worse than no
cryptgraphy, the community voted in favor of
removing all crypto.
Various alternatives to the old crypto is
being discussed in #701.
Closes#694.
Move files from src/ to src/nvim/.
- src/nvim/ becomes the new root dir for nvim executable sources.
- src/libnvim/ is planned to become root dir of the neovim library.