Report error code for incompatible version sets

[jynik]

libbladeRF needs to make it more clear that a potentially incompatible set of items (FPGA, firmare, libbladeRF) has been loaded. This is a serious usability problem that's fallen by the wayside in favor of other big tasks.

More thought on this is required on my end, certainly, as this needs to be implemented in a way that doesn't allow a user to get stuck in a situation where they can't update the firmware/FPGA (which may be autoloaded) because the lib is spitting out an error.

Generally speaking I think this will consist of the following...

• Adding a return code to indicate incompatible versions being detected
• Returning said code in bladerf_open, bladerf_open_with_metadata, and bladerf_load_fpga

I'd like to see us get away binary-only firmare and FPGA files, and move toward "images" that we already have the underlying items to support. This would allow us to check the image metadata for version info and also return the aforementioned error when a user is attempting to flash new firmware/FPGA.

[jynik]

A majority of the above items have been addressed in 634ad2820b2c6b5bcffdc04e71642ea964a85067 and 3c3c3f5e3778a20fa852fb4859f96c9313c45d28.

Moving to loading image files rather than binary blobs is for another day...