DataFlash: fixed SITL dataflash logging

block numbers are 1 based
DataFlash: added RCIN and SRVO log methods
Plane: added RCIN and SRVO logging
Rover: changed SERIAL3_BAUD to SERIAL1_BAUD

and add SERIAL2_BAUD for systems that have it
Plane: added SERIAL2_BAUD and rename SERIAL3_BAUD to SERIAL1_BAUD
AP_HAL: added get_system_id() method on Util
HAL_PX4: support get_system_id() on PX4
Plane: use log system ID if available
Rover: log system ID if available
Copter: log system ID if available
Copter: added uartD support

this also brings GCS_Mavlink.pde closer to the plane implementation
Copter: removed extra features of copter telemetry merge
Copter: added SERIAL2_BAUD and rename SERIAL3_BAUD to SERIAL1_BAUD
Copter: fix @Group for SingleCopter
Copter: rename some parameter Display Names

Also move some parameter descriptions to @User Advanced
Fence: parameter display name fix
INS: move Product ID to @User Advanced
RC_Channel: parameter @Units to pwm
Copter: parameter @Units to Percent*10
Compass: slightly relax HMC5843 calibration limits

Some users have reported Z axis values as high as 1.33.  Their compasses
seem otherwise health so extending the limits slightly.