This is a small helper function which sends the SR_DF_HEADER packet that
drivers usually emit in their hw_dev_acquisition_start() API callback.
It simplifies and shortens the hw_dev_acquisition_start() functions
quite a bit.
It also simplifies the input modules which send an SR_DF_HEADER packet, too.
This patch also automatically removes some unneeded malloc/free in some
drivers for the 'packet' and 'header' structs used for SR_DF_HEADER.
Sending an SR_DF_META packet at the start of every stream is not
mandatory; the frontend should ask for what it needs, and any extra
information the driver wants to send will come in due time.
Fix the bare minumum of whitespace/indentation/coding-style via
automatic 'indent' run, followed by some minor manual fixes.
Some more fixes and cleanups might follow later.
Bring back the original (C) lines from before the split into api.c
and protocol.[ch].
Add "Copyright (C) 2013 Lior Elazary <lelazary@yahoo.com>" since there
were nontrivial changes to those files.