* Add scheduler protection when do cleanup for a detached thread;
* Fix the object_find issue when enable module feature;
* Improve POSIX signal support and add rt_signal_wait function and POSIX sigwait interface;
* When enable finsh shell, rtthread.h header file includes the API file of finsh. Therefore, the application code can use command export feature without finsh.h file;
* Improve the comments of rtdbg.h file. In RT-Thread, just use following code to add debug log feature:
```c
#define DBG_ENABLE
#define DBG_SECTION_NAME "[ MOD]"
#define DBG_LEVEL DBG_INFO
#define DBG_COLOR
#include <rtdbg.h>
```
When close the DBG_ENABLE definition, the debug log will be closed. Otherwise, the `dbg_log(level, fmt, ...)` can be used to print debug information.
DBG_SECTION_NAME - The prefix information for each log line;
DBG_LEVEL - The debug log level;
DBG_COLOR - Whether use color log in console.
## Components
* Fix the flag issue of fopen in GNU GCC;
* Fix the pthread_detach issue when used for a detached pthread;
* Fix the _TIMESPEC_DEFINED issue in IAR 8;
* Add libc_stdio_get_console() interface for returns the fd of console;
* Move UI engine component as a standalone package;
* Add a unify TF/SD card driver on SPI device bus;
* Add soft-RTC device, therefore device can synchronize with network time and maintains the time with OS tick later;
* Change the open/fcntl/ioctl API to POSIX standard interface;
* Fix ramfs issue when update with RTT 3.0.x;
* Fix the elm fatfs umount issue; (liu2guang)
* ignore the O_CREAT flag when open a device file;
* Improve VCOM class driver in USB stack; (ChunfengMu, Aubr.Cool)
## BSP
* Fix the potential issue when enable Cortex-M hardware FPU;
* Add v2m-mps2 bsp, which is used in Keil MDK5 for Cortex-M4/M7/M23/M33 simulation;
* Add sdcard driver for stm32f10x-HAL;(liu2guang)
* Improve GNU GCC support for stm32f10x-HAL;(Xeon Xu)
* simulator bsp can be used in Windows/Visual C++ and update SDL to v2.0.7;
* Add gk7102 bsp by gokemicro;(gokemicro)
* Add allwinner F1C100s ARM9 bsp;(uestczyh222)
* Fix some issues in peripherals drive library of NXP LPC54608/i.MX RT; (Valeriy Van)
## Tools
* scons building script will automatically add `_REENT_SMALL` macro when enable newlib nanao;
* Modify building script for Python 3.x and scons 3.0
