Misc fix

Commit a6251a43 changed the serial device to check open_flag
instead of flag. So we should change the rt_kprintf counterpart as well.

fix stm32f407 uart3 TX config error

external: update freetype to 2.5.4

ymodem: fix a race-condition in handshaking

As we are sending C continuously, there is a chance that the
sender(remote) receive an C after sending the first handshake package.
So the sender will interpret it as NAK and re-send the package. So we
just ignore it and proceed.

lodepng: make the crc32 LUT const

This saves 1KiB ram usage.

Misc fix

RT_TIMER_TICK_PER_SECOND in rtconfig.h for softtime scheduler is not used.

Rt thread coing

Conflicts:
	bsp/lpc5410x/project.uvprojx

Before the project was established with RB_ROOT

Before the project is generated by rtt_root

Misc fix

ARMCC will define __GNUC__ in "GNU mode"(with --gnu command line
option). So iff __GNUC__ && !__CC_ARM is GCC.

There is no list_mem and only list_memheap when RT_USING_MEMHEAP_AS_HEAP
is enabled.

Add uart driver and finsh function