remove rt_passed_second in clock; init device driver when driver has been opened if it is not in activate status; change interrupt nest count to rt_uint8_t; add rt_console_set_device function in kservice.c (rt_kprintf function can use device right now)

git-svn-id: https://rt-thread.googlecode.com/svn/trunk@464 bbd45198-f89e-11dd-88c7-29a3b14d5316

git-svn-id: https://rt-thread.googlecode.com/svn/trunk@226 bbd45198-f89e-11dd-88c7-29a3b14d5316

git-svn-id: https://rt-thread.googlecode.com/svn/trunk@198 bbd45198-f89e-11dd-88c7-29a3b14d5316

fix the cortex-m3 context switch bug when interrupt preempts pendsv exception; add RT_LWIP_ETH_PAD_SIZE option; fix device activate flag set issue in init function.

git-svn-id: https://rt-thread.googlecode.com/svn/trunk@193 bbd45198-f89e-11dd-88c7-29a3b14d5316

git-svn-id: https://rt-thread.googlecode.com/svn/trunk@2 bbd45198-f89e-11dd-88c7-29a3b14d5316