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/hashtab.h

@@ -0,0 +1,56 @@
+#ifndef NEOVIM_HASHTAB_H
+#define NEOVIM_HASHTAB_H
+
+/* Item for a hashtable.  "hi_key" can be one of three values:
+ * NULL:	   Never been used
+ * HI_KEY_REMOVED: Entry was removed
+ * Otherwise:	   Used item, pointer to the actual key; this usually is
+ *		   inside the item, subtract an offset to locate the item.
+ *		   This reduces the size of hashitem by 1/3.
+ */
+typedef struct hashitem_S {
+  long_u hi_hash;               /* cached hash number of hi_key */
+  char_u      *hi_key;
+} hashitem_T;
+
+/* The address of "hash_removed" is used as a magic number for hi_key to
+ * indicate a removed item. */
+#define HI_KEY_REMOVED &hash_removed
+#define HASHITEM_EMPTY(hi) ((hi)->hi_key == NULL || (hi)->hi_key == \
+                            &hash_removed)
+
+/* Initial size for a hashtable.  Our items are relatively small and growing
+ * is expensive, thus use 16 as a start.  Must be a power of 2. */
+#define HT_INIT_SIZE 16
+
+typedef struct hashtable_S {
+  long_u ht_mask;               /* mask used for hash value (nr of items in
+                                 * array is "ht_mask" + 1) */
+  long_u ht_used;               /* number of items used */
+  long_u ht_filled;             /* number of items used + removed */
+  int ht_locked;                /* counter for hash_lock() */
+  int ht_error;                 /* when set growing failed, can't add more
+                                   items before growing works */
+  hashitem_T  *ht_array;        /* points to the array, allocated when it's
+                                   not "ht_smallarray" */
+  hashitem_T ht_smallarray[HT_INIT_SIZE];      /* initial array */
+} hashtab_T;
+
+typedef long_u hash_T;          /* Type for hi_hash */
+
+/* hashtab.c */
+void hash_init(hashtab_T *ht);
+void hash_clear(hashtab_T *ht);
+void hash_clear_all(hashtab_T *ht, int off);
+hashitem_T *hash_find(hashtab_T *ht, char_u *key);
+hashitem_T *hash_lookup(hashtab_T *ht, char_u *key, hash_T hash);
+void hash_debug_results(void);
+int hash_add(hashtab_T *ht, char_u *key);
+int hash_add_item(hashtab_T *ht, hashitem_T *hi, char_u *key,
+                  hash_T hash);
+void hash_remove(hashtab_T *ht, hashitem_T *hi);
+void hash_lock(hashtab_T *ht);
+void hash_unlock(hashtab_T *ht);
+hash_T hash_hash(char_u *key);
+
+#endif /* NEOVIM_HASHTAB_H */