Missing methods on the client

[tibebeselasie-mehari]

Some methods that are available on the official telegram page such as pinChatMessage, deleteMessage... are not found on the client object provided.

[m90]

The last time I added API methods to this library was in 2016 so everything that has been added to the Telegram Bot API since then is indeed missing.

I probably won't find the time to add what's missing anytime soon, but in case you (or someone else) wants to add the additional methods, I'd be happy to help and merge PRs. I think it should be a relatively easy undertaking for most of the missing methods.