fix bin/tar-entry.sh and bin/tar-year.sh, improve bin/README.md, update Makefile

It turns out that `sed -i ''` is not portable. **sigh** Replaced use of
`sed -i ''` with other portable commands in `bin/tar-year.sh`.

Changed `bin/tar-entry.sh` VERSION from "1.3.4 2024-03-27"
to "1.3.5 2024-03-28".

Changed `bin/tar-year.sh` VERSION from "1.2 2024-03-27"
to "1.2.1 2024-03-28".

Changed `bin/gen-year-index.sh` VERSION from "1.0.4 2024-03-26"
to "1.0.5 2024-03-28".

Changed `bin/sort.gitignore.sh` VERSION from "1.1.3 2024-03-26"
to "1.1.4 2024-03-28".

Added new `bin/untar-year.sh` bin tool.

Tested `make untar_year_tarball` under Linux.

Added `make sort_gitignore` to sort entry `.gitignore` files.
The `make quick_www` and `make www` actions perform `make sort_gitignore`.

Added notes to `bin/README.md` (and thus to `bin/index.html` with
recommendations of top level Makefile actions that use selected bin
tools over all entries or years).

Tested `make www form_entry_tarball form_year_tarball untar_entry_tarball
untar_year_tarball` under Linux.

TODO: Retest `make www form_entry_tarball form_year_tarball
      untar_entry_tarball untar_year_tarball` under macOS.

bin/sort.gitignore.sh

@@ -99,7 +99,7 @@ shopt -s globstar	# enable ** to match all files and zero or more directories an
 
 # set variables referenced in the usage message
 #
-export VERSION="1.1.3 2024-03-26"
+export VERSION="1.1.4 2024-03-28"
 NAME=$(basename "$0")
 export NAME
 export V_FLAG=0
@@ -430,14 +430,20 @@ if [[ -z $NOOP ]]; then
 	echo "$0: ERROR: sgi.sh failed, error: $status" 1>&2
 	exit 12
     fi
-    if [[ $V_FLAG -ge 1 ]]; then
-	echo  "$0: debug[1]: about to execute: mv -f $TMP_FILE $GITIGNORE" 1>&2
-    fi
-    mv -f "$TMP_FILE" "$GITIGNORE"
-    status="$?"
-    if [[ $status -ne 0 ]]; then
-	echo "$0: ERROR: sgi.sh failed, error: $status" 1>&2
-	exit 13
+    if cmp -s "$TMP_FILE" "$GITIGNORE"; then
+	if [[ $V_FLAG -ge 1 ]]; then
+	    echo  "$0: debug[1]: $GITIGNORE is already sorted" 1>&2
+	fi
+    else
+	if [[ $V_FLAG -ge 1 ]]; then
+	    echo  "$0: debug[1]: about to execute: mv -f $TMP_FILE $GITIGNORE" 1>&2
+	fi
+	mv -f "$TMP_FILE" "$GITIGNORE"
+	status="$?"
+	if [[ $status -ne 0 ]]; then
+	    echo "$0: ERROR: sgi.sh failed, error: $status" 1>&2
+	    exit 13
+	fi
     fi
 elif [[ $V_FLAG -ge 1 ]]; then
     echo  "$0: debug[1]: -n disabled execution of: $SGI_TOOL < $GITIGNORE > $TMP_FILE" 1>&2