Implement SDK event monitor
Move wifi status event monitor code into seperate file
(app/modules/wifi_eventmon.c)
Modify wifi lua callback registration code.
Add Functions wifi.ap.deauth and wifi.sta.getrssi
Rework wifi event monitor to use tasking interface
fix for Lua coroutine compatibility issue
Made changes Suggested by TerryE
Also, moved code that sets the default host name out of
luaopen_wifi_init and into a separate function and added a post_task_low
entry in it's place.
Replaced some if test then return error lines with
luaL_argcheck
Add check for malloc null return in wifi.eventmon
to catch out of memory errors
Philip Gladstone
dnc40085
Johny Mattsson
funshine
HuangRui