A feature update which brings the library closer to 100% webhook support
New features
- Rate limit handling
- Added `discordwebhook.File` - Attach a file to a webhook message
- Added `Webhook.modify` - Modify a webhook
- Added `Webhook.delete` - Delete a webhook
- Added `discordwebhook.WebhookMessage` This allows messages to be edited and deleted. See [the example](https://github.com/Coolo22/discordwebhook.py/blob/9d291a95cb46c87701a940cc8b1ebeed13da7adc/Examples/edit%2Bdelete_message.py)