Beta 10

New barometric pressure control attempt with enhanced smoothing and improved accuracy
New surface layer control method for improved temperature and baro accuracy in XP12 weather reports, datarefs, and other add-ons
Fixed ASXP12 crash on XP12 exit in some cases
Added Override XP12 surface variability option/feature (on by default) which allows ASXP12 to control surface variability fully
Updated documentation