- added information to several docblocks
- changed handling of request headers, added private property for this
- applied changes for improved use of require_once in the README and examples
- added `list_sites()` example
- *potential breaking changes:*
renamed `get_request_type()` and `set_request_type()` functions/methods to `get_request_method()` and `set_request_method()` respectively
- updated code and instructions for `set_guestlogin_settings()`, thanks to @stoehrmark for reporting the issue
- added list_connected_users.php example contributed by @gahujipo
- added restart_device() which replaces restart_ap(), contributed by @leonardogyn
- code styling cleanup across `Client.php`
