Silence -Wstrict-prototypes and static analyser warnings
Using "(void)" provides an explicit there-are-no-arguments prototype.
Using the exact type in "malloc(...sizeof)" is clearer and silences
warnings from clang's static analyzer. (John Marshall)
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.
