CameraStabilization: POI mode for pitch was inverted

The declination calculation uses the standard pitch representation
(position if up) but the code for camera control uses the opposite
where pitch is down.  This makes sure POI mode feeds in appropriate
inputs.
TabletControl: when entering position hold grab current location

Only checking for flight mode changes is insufficient.
TabletControl: use TabletInfoTabletModeDesiredOptions instead of uint8_t
Updated makefile instructions for compiling GCS.
Remove keyboard shortcuts from wizard. Using CTRL-V is overloading the
commonly used paste function.
GCS-UAVO browser, fixed wrong parentesis location

This bug was introduced on #581
Merge pull request #623 from guilhermito/small_uavo_browser_fix_after_messing_up

GCS-UAVO browser, fix wrong parentesis location
Merge pull request #621 from kubark42/remove-hotkeys

Remove keyboard shortcuts from wizard.
Merge pull request #611 from peabody124/poi_fix

CameraStabilization: POI mode for pitch was inverted
Merge pull request #613 from peabody124/tablet_control_ph_fix

TabletControl: when entering position hold grab current location
Added OSG build instruction.
When starting HiTL, GCS set the home location, but did not identify it
as set=true. This patch fixes the behavior, as well as a minor variable
change to improve clarity.
Changed STANDARD_AIR_SEA_LEVEL_PRESSURE from KPa to Pa.
Added MIN, MAX, and sign macros to misc_math.h. The sign macro returns -1
for values less than 0, and 1 for values greater than or equal to 0. 0 is
specifically not handled different from strictly positive numbers.
Added library functions for computing atmospheric conditions.
Fixed hostile redefinition of bool.
Fixed simulation boolean defines.
Fixes from review.
Merge pull request #536 from kubark42/misc-fixes

Misc fixes
Merge pull request #617 from kubark42/makefile-instructions

Updated makefile instructions for compiling GCS.