Settings command

[TimStewartJ]

The current implementation of the settings command features the ability to enable/disable commands per-guild.

TODO:

• Make help messages reflect command settings.
• Prevent disabling settings and help commands
• Prefix setting
• Ephemeral response settings?
• Permission settings
• Guild-wide slash command enabling
• Guild-wide regular command enabling

[TimStewartJ]

Help messages currently reflect the enabled property of commands now.

[TimStewartJ]

Ephemerality can now be set per command and guild-wide.