This adds a hwdef.dat define HAL_PROBE_EXTERNAL_I2C_BAROS. When set,
we get a new parameter GND_PROBE_EXT that is a bitmask of i2c
barometers to look for.
This allows boards that have no builtin baro to work without
rebuilding
The following is a Barometer sensor driver for the LPS25H Barometer that
is integrated in the 96Boards STM32 Sensor mezzanine board.
the update includes the .cpp and .h files of the driver as well as the
updates required in AP_Baro.cpp.
Peter Barker
Andrew Tridgell
ljwang
liorosh
mirkix