CHG: "hf mf hardnested" - fixes and additions.

CHG: "hf mf hardnested" - fixes and additions.
  - freeing candidate lists after generate_candidates calls.
  - longer timeout when waiting for responses (it takes a while to collect 58 nonces per call) From 3sec to 6sec
  - if best_first_byte[0] (best guess) has been the same for 3 nonces calls in a row, it enters the generate_candidates test.
  - when total_added_nonces increases but does not enter generate_candidates tests,  it now increases the threshold_index variable. Make the output look better

Known bugs still.
   - TestIfKeyExists sometimes crashes the client,  still after the null check.
   - proxmark3 device doesn't answer calls after entering brute_force call and fails finding a key,  where it should start collecting nonces again. This bug doesn't make sense.