Add frontiers confirmation modes, use max config difficulty internally (

#121)

* Use max config difficulty internally (PR#2218)

nanocurrency/nano-node#2218
This change was made after TOML upgrade, updating config.json to provide setting overview

* Add frontiers confirmation modes (PR#2175)

nanocurrency/nano-node#2175
This change was made after TOML upgrade, updating config.json to provide setting overview

docs/running-a-node/configuration.md

@@ -123,12 +123,13 @@ This is the main configuration file for controlling node behavior. Below is an e
         "active_elections_size": "50000", // Limits number of active elections in container before dropping will be considered (other conditions must also be satisfied), minimum value allowed is 250.
         "conf_height_processor_batch_min_time": "50", // Amount of time in ms to batch setting confirmation heights for accounts during high tps to reduce write I/O bottlenecks.
         "backup_before_upgrade": "false", // Backup ledger & wallet databases before each upgrade
-        "work_watcher_period": "5" // Time between checks for confirmation and re-generating higher difficulty work if unconfirmed, for blocks in the work watcher
+        "work_watcher_period": "5", // Time between checks for confirmation and re-generating higher difficulty work if unconfirmed, for blocks in the work watcher
+        "max_work_generate_multiplier": "256.0", // Maximum allowed difficulty multiplier for work generation (double). Used for work_generate RPC requests & internal wallet work watcher
+        "frontiers_confirmation": "auto" // Mode for force frontiers confirmation. "auto" mode (default): If not Principal Representative, start frontier confirmation process every 15 minutes; if Principal Representative, start frontier confirmation process every 3 minutes. "always": Start frontier confirmation process every 3 minutes. "disabled": Do not start frontier confirmation process
     },
     "rpc_enable": "true", // Enable (in-process or child process) or disable RPC. Out of process rpc servers can still be used if launched manually.
     "rpc": {
         "enable_sign_hash": "true",
-        "max_work_generate_difficulty": "ffffffffc0000000", // Maximum difficulty allowed on work_generate RPC requests, corresponds to 256x multiplier
         "version": "1",
         "child_process": {
             "enable": "false", // Whether the rpc server is run as a child process rather than in-process