Added option to pause game upon taking damage instead of aborting autonav

The existing functionality for disabling autonav tends to do things like abort a jump while under heavy fire, thus requiring that you restart the jump timer.  This patch adds an option to the main options menu to pause the game instead of aborting autonav.  Once unpaused, it will then wait two seconds (game-time) before either re-pausing or enabling time compression, so the player will have time to react.