clone: Add the --recurse-submodules option as alias for --recursive

Since 1.6.5 "git clone" honors the --recursive option to recursively check
out submodules too. As this option can easily be misinterpreted when it is
added to other commands like "git grep", add the new --recurse-submodules
option as an alias for --recursive so the same option can be used for all
commands recursing into submodules.

Signed-off-by: Jens Lehmann <Jens.Lehmann@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-clone.txt

@@ -12,7 +12,8 @@ SYNOPSIS
 'git clone' [--template=<template_directory>]
 	  [-l] [-s] [--no-hardlinks] [-q] [-n] [--bare] [--mirror]
 	  [-o <name>] [-b <name>] [-u <upload-pack>] [--reference <repository>]
-	  [--depth <depth>] [--recursive] [--] <repository> [<directory>]
+	  [--depth <depth>] [--recursive|--recurse-submodules] [--] <repository>
+	  [<directory>]
 
 DESCRIPTION
 -----------
@@ -167,6 +168,7 @@ objects from the source repository into a pack in the cloned repository.
 	as patches.
 
 --recursive::
+--recurse-submodules::
 	After the clone is created, initialize all submodules within,
 	using their default settings. This is equivalent to running
 	`git submodule update --init --recursive` immediately after

builtin/clone.c

@@ -66,6 +66,8 @@ static struct option builtin_clone_options[] = {
 		    "setup as shared repository"),
 	OPT_BOOLEAN(0, "recursive", &option_recursive,
 		    "initialize submodules in the clone"),
+	OPT_BOOLEAN(0, "recurse_submodules", &option_recursive,
+		    "initialize submodules in the clone"),
 	OPT_STRING(0, "template", &option_template, "path",
 		   "path the template repository"),
 	OPT_STRING(0, "reference", &option_reference, "repo",