part 2 of ?? of mw2.2 merge (still not flight-tested, so no binaries)
defaulted to looptime of 3500 (yea, yea)
rewrote baro stuff to match mwc2.2 - both supported sensors now return temperature and pressure, which is used in altitude calculation code
rewrote hmc5883 driver to include calibration inside the driver file instead of calling parts of calibration from userspace. it will now blink LED1 while calibrating
some parts remaining to do.

git-svn-id: https://afrodevices.googlecode.com/svn/trunk/baseflight@298 7c89a4a9-59b9-e629-4cfe-3a2d53b20e61