Refactor channel states:

- persisted states are saved
 - state transitions are checked
 - transient states are stored in channel.peer_state
 - new channel states: 'PREOPENING', 'FUNDED' and 'REDEEMED'
 - upgrade storage to version 21

electrum/tests/regtest/regtest.sh

@@ -90,6 +90,10 @@ if [[ $1 == "init" ]]; then
     new_blocks 1
 fi
 
+if [[ $1 == "new_block" ]]; then
+    new_blocks 1
+fi
+
 # start daemons. Bob is started first because he is listening
 if [[ $1 == "start" ]]; then
     $bob daemon -d