* minor bug fixes and documentation improvements
* do not cleanup peers if we have no online peers (probably not
connected anyway)
* do not run peer cleanup until a min
* do not spam block list on shutdown during block sync
* use correct thread decrement in peerCleanup
* added trust int to address table, not used yet
* do not crash when loading new peer profile
* removed code for defunct *address* proof of work
+ added maxStoredPeers and maxConnect config options (TODO)
+ added lastConnectAttempt to address db
+ added command to cause instant peer exchange
+ added connectCheck.txt for TODO connection testing
Kevin Froman