`addUsersToGroup` can no longer return the message id

Updated documentation and tests

Version up, thanks to @orenyomtov and @Abhinav2812

Also fixed `Client.isLoggedIn`

Version up, thanks to @gave92

Properly fixed `markAsRead`, @gave92  reminded me that I forgot to change the `True` to `'true'` when removing `encode_params`

Version up, thanks to @gave92

Fix `markAsRead` and `fetchUnread`; fixes fbchat-dev#261
Added the `ssl_verify` instance variable, which allows disabling SSL varification for proxies

Minor fix for `searchFor`. See comments on fbchat-dev#266

version up thanks to @2FWAH's PR fbchat-dev#266 fbchat-dev#267

Version up, thanks to @gave92

`fetchThreadList` is updated with a GraphQL implementation. See fbchat-dev#241

Version up, thanks to @DeltaF1

`onFriendRequest` functionality is restored

Version up, thanks to @sdnian

`fetchThreadMessages` and `listen` can now parse AudioAttachments

Fixes fbchat-dev#240, small backwards-compatablitity issue when sendi…

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