px4io: split io_handle_battery() out from io_handle_status()

ready to add vservo and rssi
uORB: added new servorail_status object

used for VSERVO and RSSI on FMUv2
px4io: added monitoring of vservo and vrssi

publish via servorail_status ORB topic
added error_count field to sensor report structures
perf: added perf_event_count() method

this allows drivers to get an event_count from a perf counter
Merge branch 'master' of github.com:PX4/Firmware into status_monitoring
drivers: report error_count in drivers where possible
Merge branch 'master' of github.com:PX4/Firmware into status_monitoring
Merged status changes
State machine fixes for HIL
Robustified flight close to waypoints
Added useful default gains
Fixed turn radius return value
Added support for dynamic turn radii
Dynamic integral resets for straight and circle mode, announcing turn radius now
Added debug output printing capabilities for IOv2
Extended file test for alignment
Merge branch 'sdtest' of github.com:PX4/Firmware into hil_usb_only
Slight fix to test, but still fails validating written data after non-aligned writes
Merge branch 'sdtest' into hil_usb_only