+upload command line in the help information(the output of command "scons
+[options] -h")
+Functions for external library management:
+PrepareLib(libname, lib = None, path = None, script = None): Check whether a
+library exists, if not, notify user to install it or try to download the source
+code and build it
+# @param libname - the name of the library try to prepare
+# @param lib - the lib(.so, .a etc) to check (a library may include more then
+# one lib, e.g. boost, includes boost_thread, boost_system ...
+# @param path - the path of the library building script, if it's not set,
+# by default, it's <src_dir>/extlibs/<libname>/
+# @param script - the building script, by default, it's 'SConscript'
+
+Download(target, url): Download source code from URL 'url' and save as 'target'.
+# @param target - the name of the source code package to be saved as
+# @param url - the URL from which to download the source code
+
+Configure(cwd, cmd): Run configure command(such as: bootstrap, configure etc.
+usually it's done before build a library)
+# @param cwd - the work directory, full path or relative path to the directory
+ where the library build script in
+# @param cmd - the command to run, can be a script or system command
+
+Install_head_file(file): Install header file(s) to <src_dir>/deps/<target_os>/include
+# @param file - the head file(s) to install
+
+Install_lib(lib): Install library binaries to <src_dir>/deps/<target_os>/lib/<arch>
+# @param lib - the library binary(.so, .a etc) to install