1. Add IAR project template and link scripts. Add missing CXX configuration for IAR tool chain in rtconfg.py.
2. Modify all link scripts, Using ITCM interface.(Changing flash start address from 0x0800_0000 to 0x0020_0000).

[libc][dlib] Add missing definition of mode_t

For using pthread with IAR tool chain

[bsp][stm32f746-Disco] Cleanup code

1. Using RT_USING_COMPONENTS_INIT and RT_USING_USER_MAIN
2. Cleanup code

code cleanup.

[DFS] fix the fd_put issue in mkdir and lseek error case.

[Kernel] change to open the console device and then set the console device.

in rt_console_set_device, open new device first and get the new device to _console_device.
我在编写程序时，在device驱动中打印log，但是使用rt_kprintf时，如果_console_device存在非空，那就执行驱动的write函数，但是这是device还没有初始化成功，但是已经提前给_console_device赋值，导致了程序无故fault，以上述修改可避开这样的矛盾。

[DeviceDrivers] Add hardware timer framework

[BSP] Add tms320dm365