This moves the verification of the proof at node startup from init.cpp
cpp to processor.cpp. As a result, the init
A factory method is used to get the error message ifor `InitError`.
This introduces a bit less
preciseminor change from the previous behavior, but an additional log line is added to specify the exact cause
of the failurewhich I consider to be an improvement: we used to check the proof only if `-enableavalanche` was set and `-avaproof` was specified, but now the proof is checked if specified even in the absence of `-enableavalanche`.