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

src/interfaces/ecpg/compatlib/informix.c

@@ -811,7 +811,7 @@ rfmtlong(long lng_val, const char *fmt, char *outbuf)
 	/* and fill the temp-string wit '0's up to there. */
 	dotpos = getRightMostDot(fmt);
 
-	/* start to parse the formatstring */
+	/* start to parse the format-string */
 	temp[0] = '\0';
 	k = value.digits - 1;		/* position in the value_string */
 	for (i = fmt_len - 1, j = 0; i >= 0; i--, j++)

src/interfaces/ecpg/pgtypeslib/dt_common.c

@@ -172,7 +172,7 @@ static const datetkn datetktbl[] = {
 	ghst
 #endif
 	{"gilt", TZ, 43200},		/* Gilbert Islands Time */
-	{"gmt", TZ, 0},				/* Greenwish Mean Time */
+	{"gmt", TZ, 0},				/* Greenwich Mean Time */
 	{"gst", TZ, 36000},			/* Guam Std Time, USSR Zone 9 */
 	{"gyt", TZ, -14400},		/* Guyana Time */
 	{"h", UNITS, DTK_HOUR},		/* "hour" */