Generalize qix-emulator input from any QKD key source

[bushsf]

Enable the qix-emulator to accept common key material from any source of keys such that the key source need only provide a binary sequence of key material. Output from the emulator will be compliant with the QIX format, except that the key id may be replaced by a hash to identify specific keys rather than a monotonically increasing integer. The idea is make the use of alternative key sources as simple as possible.