Introduce nvim namespace: Move files.

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.

src/nvim/memline.h

@@ -0,0 +1,47 @@
+#ifndef NEOVIM_MEMLINE_H
+#define NEOVIM_MEMLINE_H
+
+#include "types.h"
+#include "func_attr.h"
+
+int ml_open(buf_T *buf);
+void ml_set_crypt_key(buf_T *buf, char_u *old_key, int old_cm);
+void ml_setname(buf_T *buf);
+void ml_open_files(void);
+void ml_open_file(buf_T *buf);
+void check_need_swap(int newfile);
+void ml_close(buf_T *buf, int del_file);
+void ml_close_all(int del_file);
+void ml_close_notmod(void);
+void ml_timestamp(buf_T *buf);
+void ml_recover(void);
+int recover_names(char_u *fname, int list, int nr, char_u **fname_out);
+void ml_sync_all(int check_file, int check_char);
+void ml_preserve(buf_T *buf, int message);
+char_u *ml_get(linenr_T lnum);
+char_u *ml_get_pos(pos_T *pos);
+char_u *ml_get_curline(void);
+char_u *ml_get_cursor(void);
+char_u *ml_get_buf(buf_T *buf, linenr_T lnum, int will_change);
+int ml_line_alloced(void);
+int ml_append(linenr_T lnum, char_u *line, colnr_T len, int newfile);
+int ml_append_buf(buf_T *buf, linenr_T lnum, char_u *line, colnr_T len,
+                  int newfile);
+int ml_replace(linenr_T lnum, char_u *line, int copy);
+int ml_delete(linenr_T lnum, int message);
+void ml_setmarked(linenr_T lnum);
+linenr_T ml_firstmarked(void);
+void ml_clearmarked(void);
+int resolve_symlink(char_u *fname, char_u *buf);
+char_u *makeswapname(char_u *fname, char_u *ffname, buf_T *buf,
+                     char_u *dir_name);
+char_u *get_file_in_dir(char_u *fname, char_u *dname);
+void ml_setflags(buf_T *buf);
+char_u *ml_encrypt_data(memfile_T *mfp, char_u *data, off_t offset,
+                        unsigned size) FUNC_ATTR_NONNULL_RET;
+void ml_decrypt_data(memfile_T *mfp, char_u *data, off_t offset,
+                     unsigned size);
+long ml_find_line_or_offset(buf_T *buf, linenr_T lnum, long *offp);
+void goto_byte(long cnt);
+
+#endif /* NEOVIM_MEMLINE_H */