[test] Make tool usage easier by not requiring "--stdin"

Just default to it.  Added "--help" instead to get usage.

test/shaping/hb_test_tools.py

@@ -351,7 +351,7 @@ class UtilMains:
 	@staticmethod
 	def process_multiple_args (callback, mnemonic):
 
-		if len (sys.argv) == 1:
+		if len (sys.argv) == 1 or "--help" in sys.argv:
 			print "Usage: %s %s..." % (sys.argv[0], mnemonic)
 			sys.exit (1)
 
@@ -368,14 +368,13 @@ class UtilMains:
 					      separator = " ", \
 					      concat_separator = False):
 
-		if len (sys.argv) == 1 or ('--stdin' in sys.argv and len (sys.argv) != 2):
-			print "Usage:\n  %s %s...\nor:\n  %s --stdin" \
+		if "--help" in sys.argv:
+			print "Usage:\n  %s %s...\nor:\n  %s\n\nWhen called with no arguments, input is read from standard input." \
 			      % (sys.argv[0], mnemonic, sys.argv[0])
 			sys.exit (1)
 
 		try:
-			if '--stdin' in sys.argv:
-				sys.argv.remove ('--stdin')
+			if len (sys.argv) == 1:
 				while (1):
 					line = sys.stdin.readline ()
 					if not len (line):