fix 'crontab -e' to look at $EDITOR and not $VISUAL

--- crontab.1
+++ crontab.1
@@ -27,5 +27,5 @@
 specify a different user and/or crontab directory.  Generally the -e
 option is used to edit your crontab.  crontab will use /usr/bin/vi or
-the editor specified by your VISUAL environment variable to edit the
+the editor specified by your EDITOR environment variable to edit the
 crontab.
 .PP
--- crontab.c
+++ crontab.c
@@ -312,5 +312,5 @@
 	if (ChangeUser(user, 1) < 0)
 	    exit(0);
-	if ((ptr = getenv("VISUAL")) == NULL || strlen(ptr) > 256)
+	if ((ptr = getenv("EDITOR")) == NULL || strlen(ptr) > 256)
 	    ptr = PATH_VI;