this will allow the addition of a DataFlash_File implementation of the
DataFlash API which will store logs in a traditional filesystem. That
will align better with the PX4 design, and be more useful for fast
transfer of logs to a host computer
This makes the DataFlash erase much faster (about 6 seconds instead of
about 60 seconds).
We need to test and ensure the behaviour is equivalent apart from the
speed
this moves out all the high level logic from ArduPlane/ArduCopter to
the library. It also adds a "config page", as the last page in the
flash. This is used to check if the flash needs erasing. We only erase
now if the DF_LOGGING_FORMAT has changed.
This patch also adds a public CardInserted() method, which is used to
disable logging on APM2 if a dataflash card is not inserted
this moves all the non-hardware specific code to the parent
DataFlash_Class class, keeping the hw specific code much smaller and
simpler.
This should prevent discrepancies creeping in between APM1 and APM2
support again