• changed create_wlan function/method to not include passphrase in payload when security = "open" and passphrase = null
• fixed indentations in several places
• added custom_api_request() function/method which allows a programmer to issue custom API requests that may not yet be supported by this client (to be used with care!)
• added example demonstrating use of custom_api_request()
• removed repetitive code and optimized exec_curl() when creating the final payload, resulting in 10-20% performance increase and slightly lower memory consumption by PHP