Split header MMR (and sync MMR) out from txhashset (#3004)

* wip

* sync sort of works now

* get rid of the deadlock during compaction
there is *always* a deadlock in there when we make changes like this...

* cleanup how we rebuild the sync MMR on init

* cleanup rewind logic

* roll the "fix invalid root" changes into this PR

* move rebuild_height_pos_index into txhashset
and pass in header_pmmr for header lookups

* cleanup and remember to setup sync head on init

* cleanup unnecessary ref muts

* rebuild_height_pos_index when writing txhashset

src/bin/tui/ui.rs

@@ -182,9 +182,10 @@ impl Controller {
 			}
 
 			if Utc::now().timestamp() > next_stat_update {
-				let stats = server.get_server_stats().unwrap();
-				self.ui.ui_tx.send(UIMessage::UpdateStatus(stats)).unwrap();
 				next_stat_update = Utc::now().timestamp() + stat_update_interval;
+				if let Ok(stats) = server.get_server_stats() {
+					self.ui.ui_tx.send(UIMessage::UpdateStatus(stats)).unwrap();
+				}
 			}
 		}
 		server.stop();