Add mentionable property to ModifyGuildRoleParams

Allows roles to be configured to be mentionable, fixes #424

Revert "Implement configurable command node separators"

Implement configurable command node separators

Allow commands to use added type readers

A.K.A. "FiniteReality is a twat"

This fixes #304 over foxbot's PR for the same issue.

Parameter preconditions and typereader overriding

Resolves #302

per the following API error:
{
  "bitrate": [
    "Int value should be greater than 8000."
  ]
}

this was a big one

Fix case insensitive commands forcing parameters to return lowercase

Nickname changes/role changes are no longer sent over PRESENCE_UPDATE, making it obsolete to check for changes there.

Fixed async method

CheckPermissions was not set to async so await would not work.

Fixed Install -> commands.LoadAssembly

await commands.LoadAssembly(Assembly.GetCurrentAssembly(), map);
->
await commands.AddModulesAsync(Assembly.GetEntryAssembly());