Make AP_Logger_MAVLink use stderr, so it's easier to follow the debug
outputs without mixing with normal output. And this is also what
AP_Logger is using.
add support for log time to block logger
refactor rotation into backed. Don't start logs when erasing
correct log start logic
separate read and write points so that requesting log information does not corrupt the current log
when starting a new log stop logging first
clear the write buffer when starting a new log
insert utc time when requesting info for the current log
stop logging and request formats again when starting a new log
cope with erase happening while we are logging
keep pushing out startup messages even when format messages are done
don't log to the gcs in the io thread
don't start new logs in the io thread
don't validate logs while erasing
flush logs when stopping logging
account for page header when calculating logs sizes
don't return data when asked for more data than in the log
optimize locking and use separate semaphore to mediate ring buffer access
stop logging when the chip is full and send a notification
calculate logs sizes correctly even when they wrap
read log data correctly even when it wraps
add stats support to block logger
reset dropped when starting a new log
fail logging when the chip is full
refactor critical bufferspace checks
increase messagewriter budget to 250us and to 300us for FMT
Henry Wurzburg
Lucas De Marchi
Michael du Breuil
Pierre Kancir
Andrew Tridgell
Patrick José Pereira
Peter Barker
Andy Piper
Pierre Kancir
Tom Pittenger