I think this fixes all sync problems

add a bool to the HashAndHeight struct;
can indicate "final".  When the block market final comes in,
we don't enter wait state, but instead ask for headers.
when you don't get any headers, you wont need any blocks, and that
will assert the wait state.

shell.go

@@ -69,7 +69,7 @@ func shell() {
 	}
 
 	// once we're connected, initiate headers sync
-	err = Hdr()
+	err = SCon.AskForHeaders()
 	if err != nil {
 		log.Fatal(err)
 	}
@@ -149,18 +149,6 @@ func Shellparse(cmdslice []string) error {
 	return nil
 }
 
-// Hdr asks for headers.
-func Hdr() error {
-	if SCon.RBytes == 0 {
-		return fmt.Errorf("No SPV connection, can't get headers.")
-	}
-	err := SCon.AskForHeaders()
-	if err != nil {
-		return err
-	}
-	return nil
-}
-
 // Bal prints out your score.
 func Bal(args []string) error {
 	if SCon.TS == nil {