clean up source code:
	1. use template_initializor_c to initialize the global object template.
	2. remove function `get_require_as_handle` and `get_require_as_persitent`
	3. Rename callback function with prefix `JS_`
	4. remove function `string_to_handle_string`.
	5. rewrite `require_imp` etc. clean up the implementation.
	6. reorder the functions.

fix CMake problems:
	1.  CMake bug. install hello_world_module_doc.js in the debug mode also.
	2. add `find_package(Threads REQUIRED)` in ./CMakeLists.txt
	3.  add git submodule https://github.com/v8/v8.git
	4. update CMakeLists.txt, miminum required CMAKE 2.6
	5. add submodule libevent, make it depends on libevent, modify build.sh to build the debug mode

Open issues:
	1. try to compile the release version, but it has strange error with g++ 4.4.4 for static linking. there is no such problem with other version of 4.7.3. I won't fix it. it is the compiler problem.
	2. ctest in release mode does not work
	3. cmake/Findv8.cmake could be removed.
1. Split void_ptr.h from voba_utils,
2. hack to getData(Handle<ArrayBuffer> array_buffer)
3. implement str2ba::readString and str2ab::writeString.
4. split voba_utils.h into voba_ctro.h voba_args.h voba_cmdline.h and voba_exception.h
5. split voba_utils.cpp into voba_ctor.cc voba_args.cc voba_cmdline.cc and voba_exception.cc
6. use struct_wrapper to replace voba_ctor_base1, we should not directly use GetInternalField. We should use struct_wrapper.
clean up stdio_module
	1. renaming
	2. use ArrayBuffer instead of void_pointer.
rewrite stdio_test6 and stdio_test7
cleanup fgets.
clean up posix_module, socket_module, read/write uses ArrayBuffer.
avoid to use voba_ctro_base_ptr which is more complex.
mark voba_ctor_base_ptr1 as experimental.
deprecate alloc_module
use TypedArray::Length, so avoid the additional argument len, simplify the interface.