Rebase of changes to sensor_hil_fixedwing branch.
Change default vehicle type to fixedwing.
Fixed HIL state machine issue with reboot.
Reboot fix.
Working on comments.
Reduced stack size for mavlink receiver.
Removed last bogus references to battery voltage from sensor combined topic
Merge pull request #158 from PX4/battery_status_cleanup

Removed last bogus references to battery voltage from sensor combined topic
Fixed comment.
More fixes.
Added assertion, fixed formatting.
More formatting.
Changed fault tolerances.
Merge pull request #156 from jgoppert/sensor_hil_rebase

Rebase of changes to sensor_hil_fixedwing branch.