add logtrace component

Logtrace is a component that could output the log into either a device
or a file. It has the ability to filter the log messages according to a
pre-module level. Define RT_USING_LOGTRACE in rtconfig.h if you want to
have a try.

update libcpu/arm/cortex-m4: support lazy stack optimized.

回收main函数所用的栈空间

tools: add an option to generate cscope database

When --cscope option is given to Scons, it will generate a cscope
cross-reference database in current directory, which is useful in
Vim(and other cscope-aware text editors). For example, `scons -s
--cscope` will do nothing except generating the database. You can use
this option with other options together.

It is inspired by the `make cscope` of Linux.

Rm48x50

format s3c24x0 serial.c and mini2440 rtconfig.py

format the s3c24x0 serial.c and mini2440 rtconfig.py

完善生成codeblock工程功能。

indent format cortex-m3/cpuport.c, thank peter.uboot@gmail.com

Signed-off-by: Nvisitor83 <root@wolflouis.(none)>

udisk can be ejected

usb: add USB_MSG_PLUG_OUT event