add file that forget to submit before
auto change timer mtimercmp register on the base of RT_TICK_PER_SECOND in rtconfig.h
no flashing led
new file： ../../src/idle.c
recover old file
save sp to old thread
clear rt_thread_switch_interrupt_flag
always enable interrupt after rt_hw_context_switch
judeg the type of interrupt in trap_entry, then call handler(Machine timer interrupt of Machine external interrupt)
zhangjun