Fixed gravity settings dialog.
GCS: Fix to suppress lots of debugging messages

The rich alarms change introduced a bug which caused spewing
debug messages.
Merge pull request #377 from kubark42/gravity-dialog

Fixed gravity settings dialog.
Merge pull request #398 from peabody124/alarms_fix

GCS: Fix to suppress lots of debugging messages
Added header file with common physical constants.
Updated library functions to use physical constants file.
Updated flight modules to use physical constants file.
Updated PiOS files to use physical constants file.
Updated GCS files to use physical constants file.
Added the shared API directory to simulator targets.
Fixes for header files, floating point trig functions, and incorrect
conversions.
Added shared/api to GCS include directory.
HomeLocation: Remove unused "g_e" field

We can add it back in if we start using it, but then we need
to use it reliably.  As it was this value was simply set and
then wasted memory.
Fixed missing newline.
Merge pull request #399 from peabody124/no_ge

HomeLocation: Remove unused "g_e" field
Calibration: Add doxygen header describing class function
Resolved merge conflict.
Merge pull request #328 from kubark42/phys-constants

Group all physical constants into one file