The driver might forget to set the type of the print. Catch that error a
bit earlier rather than failing when the API user tries to load it from
disk again.
This was added as alias to the error check, but given we're passing to the
callback both the error and the match itself, we can just avoid adding an
extra parameter that could be confusing (as may imply that the matching
happened).
Also clarify the documentation and ensure that the match value is properly
set in tests.
It is a good idea to report match results early, to e.g. log in a user
immediately even if more device interaction is needed. Add new _full
variants for the verify/identify functions, with a corresponding
callback. Also move driver result reporting into new
fpi_device_{identify,verify}_report functions and remove the reporting
from the fpi_device_{identify,verify}_complete calls.
Basic updates to code is done in places. Only the upekts driver is
actually modified from a behaviour point of view. The image driver code
should be restructured quite a bit to split the reporting and only
report completion after device deactivation. This should simplifiy the
code quite a bit again.
Some things were odd with regard to the ownership of passed objects. Try
to make things sane overall, in particular with the possible floating
FpPrint reference.
In order to be able to test the private device code (used by drivers) we
need to have that split a part in a different .c file so that we can compile
it alone and link with it both the shared library and the test executables.
Redefine fp_device_get_instance_private for private usage, not to move
the private struct as part of FpDevice.
