tools: Change LogAnalyzer tabs to spaces (per APM python conventions)
CameraFeedback: alt rel/msl, renamed CAMERA_EVENT

- include both “alt_msl” and “alt_rel”
- rename CAMERA_EVENT to CAMERA_STATUS
- clarify comments regarding message origin and order
- change pitch/roll/yaw to be camera rather than vehicle, earth frame
GCS_MAVLink: regenerate headers
tools: Allow LogAnalyzer to read from stdin rather than just files

Use - intead of the filename
tools: Allow LogAnalyser to emit its xml to stdout.

If you use - as the name for the output file.
tools: LogAnalyzer fixes to work with pipes as input

seek is not supported on pipes (and not needed in this case)
tell is also not supported, so count bytes on our own
tools: LogAnalyser, ensure error msgs go to stderr not stdout
tools: LogAnalyser if we fall off end of GPS data, return a valid time

Found cases where the loiter test would fail with some flights if
the vehicle never left that mode.  Don't use None in that case
tools: my change to use stdin, broke reading logs that have no header

This fixes it (I'm careful to avoid seeking)
GCS_MAVLink: fixed missing header
modified .gitignore to ignore .vrx and .hex files
VRBRAIN: enabled the compilation of module bl_update for bootloader update from nuttx
VRBRAIN: added automatic update of bootloader from SD at startup
VRBRAIN: some not important adjustments
VRBRAIN: renamed external and on board drivers for MPU6000 and HMC5883 sensors
VRBRAIN: added filter dfu
AP_HAL_VRRBAIN: added comment
VRBRAIN: deactivated error on HMC5883 start
VRBRAIN: included module esc_calib for ESC's calibration from shell
VRBRAIN: deleted unnecessary customizations