don't exit on mismatching checkpoint when block isn't current head

prevents occasional crashes when we receive an invalid block at a low height
command client: don't autostart server, increase reconnect interval
cleanup logging
cleanup default storage location to take into account different networks
typo
create network-specific data dir if it doesn't exist
handle getaddr and getblocks packets
cleanup node config, separate connection limit for in/out, fixes for incoming connections
serialize and store AuxPow with Blocks