1. Fix wrong reason code in 'WIFI_EVENT_AP_STADISCONNECTED' event
2. cleanup in softAP for disconnecting connected station
3. Update examples to display reason while processing WIFI_EVENT_AP_STADISCONNECTED event
This commit updates the visibility of various header files and cleans up
some unnecessary inclusions. Also, this commit removes certain header
include paths which were maintained for backward compatibility.
esp_netif_init() returns standard esp_err_t error code (unlike tcpip_adapter init), so shall be checked for the return value
Also to make the initialization code more consistent.