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_defs.h

@@ -0,0 +1,59 @@
+#ifndef NEOVIM_MEMLINE_DEFS_H
+#define NEOVIM_MEMLINE_DEFS_H
+
+#include "memfile_defs.h"
+
+/*
+ * When searching for a specific line, we remember what blocks in the tree
+ * are the branches leading to that block. This is stored in ml_stack.  Each
+ * entry is a pointer to info in a block (may be data block or pointer block)
+ */
+typedef struct info_pointer {
+  blocknr_T ip_bnum;            /* block number */
+  linenr_T ip_low;              /* lowest lnum in this block */
+  linenr_T ip_high;             /* highest lnum in this block */
+  int ip_index;                 /* index for block with current lnum */
+} infoptr_T;    /* block/index pair */
+
+typedef struct ml_chunksize {
+  int mlcs_numlines;
+  long mlcs_totalsize;
+} chunksize_T;
+
+/* Flags when calling ml_updatechunk() */
+
+#define ML_CHNK_ADDLINE 1
+#define ML_CHNK_DELLINE 2
+#define ML_CHNK_UPDLINE 3
+
+/*
+ * the memline structure holds all the information about a memline
+ */
+typedef struct memline {
+  linenr_T ml_line_count;       /* number of lines in the buffer */
+
+  memfile_T   *ml_mfp;          /* pointer to associated memfile */
+
+#define ML_EMPTY        1       /* empty buffer */
+#define ML_LINE_DIRTY   2       /* cached line was changed and allocated */
+#define ML_LOCKED_DIRTY 4       /* ml_locked was changed */
+#define ML_LOCKED_POS   8       /* ml_locked needs positive block number */
+  int ml_flags;
+
+  infoptr_T   *ml_stack;        /* stack of pointer blocks (array of IPTRs) */
+  int ml_stack_top;             /* current top if ml_stack */
+  int ml_stack_size;            /* total number of entries in ml_stack */
+
+  linenr_T ml_line_lnum;        /* line number of cached line, 0 if not valid */
+  char_u      *ml_line_ptr;     /* pointer to cached line */
+
+  bhdr_T      *ml_locked;       /* block used by last ml_get */
+  linenr_T ml_locked_low;       /* first line in ml_locked */
+  linenr_T ml_locked_high;      /* last line in ml_locked */
+  int ml_locked_lineadd;            /* number of lines inserted in ml_locked */
+  chunksize_T *ml_chunksize;
+  int ml_numchunks;
+  int ml_usedchunks;
+} memline_T;
+
+#endif // NEOVIM_MEMLINE_DEFS_H