* wifi: remove pseudo-modes for shutdown
make shutdown and resumeFromShutdown public
removes extra code from the mode handler and include method description
in the docs
* typo
* dup
* typos
* reference only shutdown() & resumeFromShutdown()
prefer to have some specific function, don't simply chain into sleep
update examples and docs
* safeguard raw sdk config usage
* Disable WiFi at boot by default
* +define WIFI_IS_OFF_AT_BOOT
* remove now useless example
* mv enableWiFiAtBootTime() to core_esp8266_features.h
* sync with master
* per @earlephilhower review: a file was missing
* doc
* WiFi persistence is now false by default
* fix doc
* ditto
* doc: remove sphinx warnings (fix links and formatting)
* fix link name
* fix doc
* legacy: restore persistence
* undeprecate preinit()
* move force modem up to when mode has changed (per @mcspr review)
* do not wake up from sleep when mode if OFF
* fix doc per review
Improve resume speed by passing in last known BSSID
Provide a simpler example for WIFI_SHUTDOWN/WIFI_RESUME
Add documentation for WIFI_SHUTDOWN and WIFI_RESUME.
