Fix the bug #42 - replace the heap_2.c to heap_4.c
Fix the bug #42 - replace the heap_2.c to heap_4.c

*heap_4.c implement a better algorithm about the memory management

ming6842/firmware-new,shengwen1997/moonbear-firmware,shengwen1997/moonbear-firmware,zxc2694/moonbear-firmware,fboris/firmware,ming6842/firmware,ming6842/firmware-new,UrsusPilot/firmware,zxc2694/moonbear-firmware,ming6842/firmware,fboris/firmware,shengwen1997/moonbear-firmware,fboris/firmware,UrsusPilot/firmware,UrsusPilot/firmware,ming6842/firmware,zxc2694/moonbear-firmware,ming6842/firmware-new