Tighten Main(), and use pager by default

The use of `[ -t 1 ]` won't check for interactivity, rather, whether
STDOUT is viable? If so, it might be best to check the `$-` variable
(I think that's it) for the `i` character, like the standard default
Debian `.bashrc` interactivity checks. Or, my preference, check the
`$PS1` is not empty, which works well in my own `.bashrc` file.

The `Main()` function was spread a bit too far, but is now more
appropriate; has no real impact, just clarify when reading.

Although the use of less(1) pager is enabled by default, it can be
disabled now with the `--no-pager|-P` flags.

tests/lenchk

@@ -16,11 +16,11 @@ Usage(){
 		  -h, --help               - Display this help information.
 		  -D, --no-subdirs         - Ignore the 'sheets/_*' subdirectories.
 		  -N, --no-preview         - Omit the preview of each triggered line.
+		  -P, --no-pager           - Do not use less(1) to page the output.
 		  -S, --no-summary         - Omit the summary before $Progrm exits.
 		  -W, --no-whilelist       - Do not use the whitelist file.
 		  -c, --colorize           - Provide color via esscape sequences.
 		  -l, --limit [INT]        - Override the limit of 80 columns.
-		  -p, --pager              - Use less(1) to page the output.
 		  -w, --wl-file [FILE]     - Use an alternative whitelist file.
 
 		  Files to whitelist must be placed line-by-line; one path per line.
@@ -55,8 +55,8 @@ while [ "$1" ]; do
 			if ! [[ $MaxCols =~ ^[0-9]+$ ]]; then
 				Err 1 'Invalid column maximum provided.'
 			fi ;;
-		--pager|-p)
-			DoLess='True' ;;
+		--no-pager|-P)
+			NoPager='True' ;;
 		--no-preview|-N)
 			NoPreview='True' ;;
 		--colorize|-c)
@@ -94,20 +94,20 @@ case $PWD in
 		Err 1 "Not within the 'cheat.sheets/tests' directory." ;;
 esac
 
-Main(){
-	Dirs=(../sheets/*)
-	[ "$NoSubDirs" == 'True' ] || Dirs+=(../sheets/*/*)
-
-	# If the whitelist file exists, use it, unless whitelisting is disabled.
-	# Keeping this test outside of the loop to avoid unnecessary processing.
-	if [ "$NoWhiteList" != 'True' ] && [ -f "$WLFile" ]; then
-		# Read the whitelist file, line-by-line, generating an array thereof.
-		Whitelisted=()
-		while read; do
-			Whitelisted+=("../${REPLY#cheat.sheets/}")
-		done < "$WLFile"
-	fi
+Dirs=(../sheets/*)
+[ "$NoSubDirs" == 'True' ] || Dirs+=(../sheets/*/*)
 
+# If the whitelist file exists, use it, unless whitelisting is disabled.
+# Keeping this test outside of the loop to avoid unnecessary processing.
+if [ "$NoWhiteList" != 'True' ] && [ -f "$WLFile" ]; then
+	# Read the whitelist file, line-by-line, generating an array thereof.
+	Whitelisted=()
+	while read; do
+		Whitelisted+=("../${REPLY#cheat.sheets/}")
+	done < "$WLFile"
+fi
+
+Main(){
 	for File in "${Dirs[@]}"; {
 		[ -f "$File" ] || continue
 
@@ -172,7 +172,7 @@ Main(){
 	fi
 }
 
-if [ "$DoLess" == 'True' ]; then
+if [ -t 1 -a "$NoPager" != 'True' ]; then
 	# Redirecting STDERR to address less(1) bug causing summary to display
 	# where it shouldn't; only seems to happen when colorization is enabled.
 	Main 2>&1 | less -r