this should be handled by #520

Instead of using fields, we will now use properties (that must have a setter).

This allows users to flag a field with InjectAttribute, and when the module is created at runtime, this field will be filled in with the object from the dependency map.

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

Parameter preconditions and typereader overriding

Resolves #302

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.

*facepalm*

This commit also adds a TypeReaders property to CommandService, so
it is possible to see all of the registered TypeReaders. This makes
it possible for users to implement their own parsing instead of
using the built-in parsing.

Seems I missed this originally, whoops.

The previous name was causing some confusion

Adds Timestamps to embeds, and removes Image and Thumbnail-Builders

Currently, commands are case-sensitive. This PR allows for commands to be case insensitive (which is now the default option).

Close the WebSocket when disconnecting

Throw an exception when creating a Color with an invalid float value

Conflicts:
	src/Discord.Net.Commands/CommandService.cs

For a command to use the DefaultRunMode, it must now have it's RunMode set to RunMode.Default (this is the default value on CommandAttribute now).

This prevents a 400 when sending a malformed color to Discord.