Generic Updates

A number of generic style and documentation improvements.
Updated minimum dependency versions.

2.1.0

• Re-add delivery method for QueuedWebhook.

2.0.0

• Updated Unit Tests (new workflow & 100% code coverage)
• Moved Color from External to Internal.
• Added phpunit testing scripts.
• Changed PHPUnit dev dependency.
• Fixed Color::fromDecimal not working properly.
• Fixed arg order for EmbedImage/EmbedVideo and related functions.
• Removed "deliver" function from webhook class, now handled in queuedwebhook.

Queued Webhooks

• Better unit testing.
• Changed Coverage Driver
• Add queued webhook class.
• Add InvalidArgumentException when transposing ID and Token.
• Separate payload creation and execution.

1.1.3

Minor cleanup and prep for github.