Change QEMU_STM32 path.
Exexute gdbauto directly.
Add .gitignore to ignore some binary file.
Remove romfs task, Create shell task. Support gdb to automatically debug.
Enable serial port RX. Add gdbscript and Makefile in previous commit.
Serial port can be used by fio.
Support puts
1)disable built-in functions (-ffreestanding)
2)import strlen from rtenv
3)change some inculded head file in string-util.c
Import strcmp, itoa from rtenv. not test yet.
Rename string-util to string. Correct puts parameter and return value.
Merge linenoise into my branch.

Merge branch 'master' of github.com:shengwen1997/freertos into linenoise_shell

Conflicts:
	main.c
	stm32_p103.c
	string.c
Unify ident in linenoise.c and string.c
Known bug: If user move cursor to left edge of terminal,
It will crash.
Use fio_read and fio_write. It doesn't access USART directly.
Move puts to linenoise.c and rename it.
the puts_base will be handle by serial_ops
Remove unused head file main.h.
Support Left arrow and Right arrow
Support History
1)Merge history relative function to my branch
2)Merge some memory operation

Merge branch 'master' of github.com:shengwen1997/freertos into linenoise_shell

Conflicts:
	Makefile
	linenoise.c
	string-util.c
	string.c
Support up and down arrows to navigate history
Bug:up or down arrows + (a little time ) + space + enter
This action sometimes will break the terminal. And terminal could
not show any characters anymore.
Rearrange codes in linenoise.c
Use enum to represent all of keying action
Fix a bug: Missing the first word of prompt message.
In previous version, If user move cursor, It will miss one
character of prmpt meassage or crash.