Fix inconsistencies and typos in the tree

This is numbered take 7, and addresses a set of issues around:
- Fixes for typos and incorrect reference names.
- Removal of unneeded comments.
- Removal of unreferenced functions and structures.
- Fixes regarding variable name consistency.

Author: Alexander Lakhin
Discussion: https://postgr.es/m/10bfd4ac-3e7c-40ab-2b2e-355ed15495e8@gmail.com

contrib/cube/cube.c

@@ -100,7 +100,7 @@ bool		g_cube_leaf_consistent(NDBOX *key, NDBOX *query, StrategyNumber strategy);
 bool		g_cube_internal_consistent(NDBOX *key, NDBOX *query, StrategyNumber strategy);
 
 /*
-** Auxiliary funxtions
+** Auxiliary functions
 */
 static double distance_1D(double a1, double a2, double b1, double b2);
 static bool cube_is_point_internal(NDBOX *cube);

contrib/intarray/_int.h

@@ -85,12 +85,6 @@ typedef struct
 
 #define GETSIGN(x)		( (BITVECP)( (char*)x+GTHDRSIZE ) )
 
-/*
- * types for functions
- */
-typedef ArrayType *(*formarray) (ArrayType *, ArrayType *);
-typedef void (*formfloat) (ArrayType *, float *);
-
 /*
  * useful functions
  */

contrib/ltree/ltxtquery_io.c

@@ -368,7 +368,7 @@ queryin(char *buf)
 		state.str = tmp;
 	}
 
-	/* set user friendly-operand view */
+	/* set user-friendly operand view */
 	memcpy((void *) GETOPERAND(query), (void *) state.op, state.sumlen);
 	pfree(state.op);
 

contrib/pgstattuple/pgstatindex.c

@@ -727,7 +727,7 @@ pgstathashindex(PG_FUNCTION_ARGS)
 }
 
 /* -------------------------------------------------
- * GetHashPageStatis()
+ * GetHashPageStats()
  *
  * Collect statistics of single hash page
  * -------------------------------------------------