APM_OBC: adjusted docs for FS_HB_PIN

thanks to Warren for the question
AP_Common: moved map_baudrate() into AP_Common

this version supports a much wider range of baudrates
GCS_MAVLink: moved main update() routine into GCS_Common.cpp

this fixes a common timeout error with loading large missions, and
means less per-vehicle code
Plane: changed baudrate parameters to 16 bit
Plane: update baud rate parameter descriptions
Plane: updates for new GCS_MAVLink API
Copter: change baudrates parameters to 16 bit
Copter: update baud rate parameter descriptions
Copter: updates for new GCS_MAVLink API
Rover: change baudrates to 16 bit

allows for much higher serial baud rates
Rover: update baud rate parameter descriptions
Rover: updates for new GCS_MAVLink API
AntennaTracker: updates for new GCS_MAVLink API
AutoTest: add -j option to sim_vehicle

new option controls the number of processors used during compile
AC_WPNav: fix divide by zero when origin and dest are same location
Copter: Added enabled(bool) function to AP_RangeFinder_analog class
-to be able to Enable and Disable with Mavlink/GCS because _enabled flag is Private in class.
Copter: Analog Sonar Support

Added sonar support using the AP_Rangfinder_analog class instead of the
Maxbotix class.  This brings to same as arduplane and ardurover.  This
class is much nicer because we can tweek sonar values through GCS
parameters.  Downside is now sonar selection is not trivial, may need to
implement simple config on GCS side or add a wiki for default settings
of most common analog sonars.
-Added enabled(bool) setter function to AP_Rangefinder_analog in order
to dynamically enable and disable sonar at runtime with chan7 or chan 8 options
-Fixed sonar_alt and sonar voltage reports to mavlink GCS, now displays
in mission planner correctly.
-User should set max_distance in parameters to appx 60% of max for
reliability reasons, because built in 60% is removed. (Less is better)
-Added voltage and filtered report to CLI Test Sonar
-Added Mode filter to read_sonar funtion to help filter out and smooth random spikes.

*Tested on Pixhawk, sonar pin 15 maxbotix MB1240XL, scale factor 2.42
*Not tested on APMx (I don't have one)
Copter: Moved sonar mode filter before health check