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/undo_defs.h

@@ -0,0 +1,68 @@
+#ifndef NEOVIM_UNDO_DEFS_H
+#define NEOVIM_UNDO_DEFS_H
+
+#include "pos.h"
+
+/* Structure to store info about the Visual area. */
+typedef struct {
+  pos_T vi_start;               /* start pos of last VIsual */
+  pos_T vi_end;                 /* end position of last VIsual */
+  int vi_mode;                  /* VIsual_mode of last VIsual */
+  colnr_T vi_curswant;          /* MAXCOL from w_curswant */
+} visualinfo_T;
+
+typedef struct u_entry u_entry_T;
+typedef struct u_header u_header_T;
+struct u_entry {
+  u_entry_T   *ue_next;         /* pointer to next entry in list */
+  linenr_T ue_top;              /* number of line above undo block */
+  linenr_T ue_bot;              /* number of line below undo block */
+  linenr_T ue_lcount;           /* linecount when u_save called */
+  char_u      **ue_array;       /* array of lines in undo block */
+  long ue_size;                 /* number of lines in ue_array */
+#ifdef U_DEBUG
+  int ue_magic;                 /* magic number to check allocation */
+#endif
+};
+
+struct u_header {
+  /* The following have a pointer and a number. The number is used when
+   * reading the undo file in u_read_undo() */
+  union {
+    u_header_T *ptr;            /* pointer to next undo header in list */
+    long seq;
+  } uh_next;
+  union {
+    u_header_T *ptr;            /* pointer to previous header in list */
+    long seq;
+  } uh_prev;
+  union {
+    u_header_T *ptr;            /* pointer to next header for alt. redo */
+    long seq;
+  } uh_alt_next;
+  union {
+    u_header_T *ptr;            /* pointer to previous header for alt. redo */
+    long seq;
+  } uh_alt_prev;
+  long uh_seq;                  /* sequence number, higher == newer undo */
+  int uh_walk;                  /* used by undo_time() */
+  u_entry_T   *uh_entry;        /* pointer to first entry */
+  u_entry_T   *uh_getbot_entry;   /* pointer to where ue_bot must be set */
+  pos_T uh_cursor;              /* cursor position before saving */
+  long uh_cursor_vcol;
+  int uh_flags;                 /* see below */
+  pos_T uh_namedm[NMARKS];              /* marks before undo/after redo */
+  visualinfo_T uh_visual;       /* Visual areas before undo/after redo */
+  time_t uh_time;               /* timestamp when the change was made */
+  long uh_save_nr;              /* set when the file was saved after the
+                                   changes in this block */
+#ifdef U_DEBUG
+  int uh_magic;                 /* magic number to check allocation */
+#endif
+};
+
+/* values for uh_flags */
+#define UH_CHANGED  0x01        /* b_changed flag before undo/after redo */
+#define UH_EMPTYBUF 0x02        /* buffer was empty */
+
+#endif // NEOVIM_UNDO_DEFS_H