Delete structs.h by spliting it and moving code to other headers

Here's the list of squashed commits (for more info, see PR #378).

 - Define guicolor_T as a typedef in syntax.h
 - Move a big chunk of code from structs.h to buffer_defs.h
 - Move aco_save_T from structs.h to fileio.h
 - Move option_table_T from structs.h to hardcopy.h

	Aditionally:

	 - Move the printer_opts global to hardcopy.c
	 - Delete structs.h. Include buffer_defs.h where structs.h was included
	   before.
	 - Add header guards to option_defs.h

 - Put mark types and constants in new mark_defs.h
 - Move undo structs to undo_defs.h
 - Move memfile structs to new memfile_defs.h
 - Move expand_T and cmdmod_T to ex_cmds_defs.h
 - Move memline_T to memline_defs.h
 - Move many defs and types to ex_eval.h
 - Move syntax related types to syntax_defs.h
 - Move struct memfile to memfile_defs.h
 - struct buffblock and struct buffheader moved back to buffer_defs.h
 - Move some datatypes to hashtab.h and eval_defs.h
 - Move the buffer_defs.h include and TODOs for remaining unrelated types in buffer_defs.h

1 files changed, 38 insertions, 0 deletions

diff --git a/src/hashtab.h b/src/hashtab.h
index edc3f0a88f..bdcb5a0a2f 100644
--- a/src/hashtab.h
+++ b/src/hashtab.h
@@ -1,5 +1,43 @@
 #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);