While this may reduce esp_wifi.h file readability for people who don't have a "go to definition" function in their editors, this is needed to decouple esp_wifi and esp_event headers, and possibly other headers which may use wifi types in the future.
- put contents of a few headers into c++ guard blocks
- fix off-by-one error in do_global_ctors
- remove system_init from startup code (should be called from main)
2. Add struct station_list into tcpip_adapter layer
3. When ap -L cmd is received, get mac address from mac layer first and then search ip address based on mac address on dhcp layer.
