New command parameter to enforce usage in private chats only.

Update readme to state of 0.46.0

Fix #567

fix get command from type 'new_chat_members'

Update README.md

Scheduler patch

Add 'cleanup' command

Rewrite cleanup command and take prefixed database tables into account.

Bot API 3.1

Closes #550

Make Request::encodeFile public, as it's needed to send files, letting users make use of it.

Keep track of methods that need a dummy parameter for some cURL versions to function properly.

Callbacks can be added to be executed when callback queries are called.

Introduce helper commands for all Update Entity types

This makes accessing the required Entity objects much easier.

Update changelog to include (hopefully) all changes.