Indexer should try to reconnect to the btc node after losing connection

[aph5nt]

conditions:

• bitcoincore qt running and syncing main net blockchain
• indexer syncing with the local node
• nbitcoin.indexer version = v2.0.7.16

[NicolasDorier]

Actually it already does except for the initial connection.
Once started, you can freely kill your bitcoin node and restart, without complains from the indexer.