Baro MS5611 interface for Lisa M/Lia - SPI, I2C, Aspirin I2C

* I2C - works with Aspirin 2.1, we have to define MPU6000_NO_SLAVES, e.g. no magnetometer on Aspirin
* SPI - works with Aspirin 2.2
* generic - reading of barometers is done through Aspirin aux I2C (for Aspirin 2.1)

rotorcraft.makefile - here we choose which bus to use, if you have a better idea how to decide let me know

aspirin makefile - had to add a check for duplicities in ap.srcs and ap.CFLAGS, otherwise there was multiple definition of spi interfaces. Would be probably better to add this check for duplicities just before passing ap.CFLAGS and ap.srcs to compiler, so if you have a better idea, let me know...

main.c - default baro frequency is 100, which corresponds to roughly 20 baro updates per second, which is maximal possible value for highest precision pressure calculation on MS5611