Improved `sde up` to assume sde up tree only when called without arguments, but sde up pkg when called with arguments

bin/sde-update

@@ -25,7 +25,7 @@
 command='update'
 
 if [ $# -eq 0 ]; then
-	# assuming default
+	# assuming update tree
 	discriminator='tree'
 elif [ "$1" = "--help" ]; then
 	sde_wrapper_discriminator_help "$command"
@@ -33,8 +33,8 @@ elif [ "$1" = "--help" ]; then
 else
 	discriminator=$( sde_wrapper_discriminator "$command" "$1" )
 	if [ -z "$discriminator" ]; then
-		# assuming default
-		discriminator='tree'
+		# assuming update package
+		discriminator='package'
 	else
 		shift;
 	fi