Update main.cpp
Update main.cpp

Changed covariance matrix and states to shared variables
vergil1874/InertialNav,flyingk/InertialNav,zlongshen/InertialNav,priseborough/InertialNav,zlongshen/InertialNav,vergil1874/InertialNav,flyingk/InertialNav,priseborough/InertialNav,AlexHAHA/InertialNav,zlongshen/InertialNav,priseborough/InertialNav,vergil1874/InertialNav,ek99800/InertialNav,ek99800/InertialNav,flyingk/InertialNav,ek99800/InertialNav,flyingk/InertialNav,AlexHAHA/InertialNav,AlexHAHA/InertialNav,priseborough/InertialNav