System: add support for ChibiOS
pios/stm32f4xx: add support for ChibiOS
pios/common: add pios_freertos_transition
pios/stm32f4xx: add pios_freertos_transition_priv.h
pios/stm32f30x: add support for ChibiOS
ChibiOS: disable stm32f30x usb irq relocation for legacy compatibility
all flight: use pios_heap
pios_mpu6000: use worker thread
pios_l3gd20: use worker thread
fw_flyingf3: switch to ChibiOS
fw_quanton: switch to ChibiOS
fw_sparky: switch to ChibiOS
fw_revomini: switch to ChibiOS
osx pios_heap: added stub for PIOS_heap_get_free_size
posix pios_heap: added stub for PIOS_heap_get_free_size
tests/logfs: use pios_heap
taskmonitor: add support for ChibiOS