- 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
- added several monthly stats methods: `stat_monthly_gateway()`, `stat_monthly_site()`, `stat_monthly_aps()`, `stat_monthly_user()`, thanks go to @Roel Janssens for spotting these MongoDB collections
- test for `object` or `resource` in `get_curl_resource()`, closes PR #82 submitted by @banakito
- applied change to comments in `example/modify_smartpower_pdu_outlet.php` based on a suggestion by @thesohoguy
- removed unnecessary variable from `list_apgroups()`, thanks go to Stephen Davies for reporting
- added an optional parameter $ap_group_ids to the `create_wlan()` function/method for UniFi controller versions 6.0.X and higher, thanks go to Stephen Davies for contributing
- changed several references from UniFi SDN controller to UniFi Network controller
- added optional payload parameter to the list_alarms() method/function, contributed by @MikeSiekkinen through PR #68
- added example showing how to disable/enable a UniFi switch port
- updated restart_device() function/method, thanks go to @leonardogyn for reporting this
- added example to modify outlet settings on a UniFi SmartPower PDU Pro, thanks go to @panthergm for providing access
