make the accZ lpf used for althold configurable

set the variable accz_lpf_cutoff to the desired cutoff frequency
this can help to make althold smoother on copters with lots of
vibrations
althold constants updated

baro velocity now limited to 15m/s
d-term is now smaller
slow change althold now controls velocity directly

The throttle stick input now directly sets the vertical velocity
setpoint of the copter. (alt_hold_fast_change = 0)
Merge pull request #150 from luggi/better_althold

Better althold
fixing multiPPM/PWM maps for CJMCU
new Baseflight PID

full gyro scale is used now
and a new pid with float calculations and proper units is added based on PIDrewrite
eeprom size is also increased from 1kB to 2kB

Conflicts:
	src/config.c
	src/imu.c