Improve print_data structure and on-disk format

Drivers now have an ID number. These will be assigned by me and documented
on the wiki. 0 cannot be used.

Drivers now define a devtype for each device they initialise. This is to
cope with the situation where a driver can support varying devices where
their print data is incompatible (i.e. image scaling is totally changed).
This doesn't apply to any existing supported devices.

Print data no longer includes driver name, and includes driver ID instead.

Paths to saved print data now include driver ID and devtype, and no longer
include driver name.

APIs exposed for converting a print_data into a blob which can then
be loaded back again later. Useful for systems who don't want to use
my simple storage system (which is only aimed at a single user).

File format is now defined and will be documented on the wiki. The header
is larger as we can no longer rely on directory paths in all scenarios.

Print data compat check now checks devtype and driver ID.

TODO

@@ -1,6 +1,5 @@
 LIBRARY
 =======
-fingerprint data classifcation by device or device type
 identification
 external API documentation
 test suite against NFIQ compliance set
@@ -8,7 +7,9 @@ test suite against NFIQ compliance set
 DRIVERS
 =======
 Sunplus 895 driver
-AES3501 driver
+AES1610 driver
+AES2501 driver
+AES3400/3500 driver
 ID Mouse driver
 Support for 2nd generation MS devices
 Support for 2nd generation UPEK devices
@@ -17,10 +18,12 @@ IMAGING
 =======
 aes4000 doesn't work very well, maybe due to small minutia count?
 PPMM parameter to get_minutiae seems to have no effect
+nbis minutiae should be stored in endian-independent format
+return images with standard enroll/verify calls
 
 MISC
 ====
 upekts/thinkfinger relicensing (GPL --> LGPL)
 make library optionally asynchronous and maybe thread-safe
 pkg-config file
-
+nbis cleanups