Holy Smokes! It's YouTube!

Changed

• !song request no longer allows one extra request to enter the queue. (#33)
• Avoid playing the same songs over and over (#35).
• Fix off-by-one check in currency transfer (!currency give <user> <amount>).
• Only non-moderator and non-streamer chat bumps the idle counter.
• URL whitelist is now stored in a setting irc/whitelisted-hosts (#37).
• Massively improved settings and schema management.
• Settings are now parsed from chat, meaning they are validated and doesn't have to be JSON.
• !song request can now search for YouTube videos through !song request youtube:<query>.

Added

• !admin version to check current setmod-bot package version. (#32)
• Setting for controlling player feedback in chat (player/chat-feedback).
• Setting for controlling overlay update interval (player/song-update-interval).
• !admin settings for reading and writing settings through chat.
• Introduced the setting player/detached to detach the player. (#27)
• Confirmation response when performing !song open and !song close. (#36)
• !admin push <key> <value> to insert values into settings which are collections.
• !admin delete <key> <value> to delete values from settings which are collections.
• Group management and the ability to enable and disable commands (!command), aliases (!alias) and promotions (!promo).
  • !<thing> enable <name> - Enable the given command.
  • !<thing> disable <name> - Disable the given command.
  • !<thing> group <name> - Get the current group.
  • !<thing> group <name> <group> - Set the current group.
  • !<thing> clear-group <name> - Remove from all groups.
  • !admin enable-group <group> - Enable all commands, promotions, and aliases belonging to the specified group.
  • !admin disable-group <group> - Disable all commands, promotions, and aliases belonging to the specified group.
• Experimental support for requesting YouTube songs and associated settings.
• player/duplicate-duration to enforce a minimum duration between requesting duplicates songs.
• Added song/*/min-currency, for a minimum currency limit to request songs.
• Added song/*/subscriber-only and song/subscriber-only to limit song requests to subscribers only.