New wifi config options with persistence

[MightyPork]

Implemented, but not exposed outside atm:

• transmit power
• static IP, mask, gw
• own IP, mask, gw in AP mode
• own hidden AP
• own AP password (WPA2 PSK)
• hostname (does not seem to have any effect, maybe not that useful)

TODO:

This all must be stored to flash via persistence and loaded on startup.
some things like rf power and static IP are not stored by ESP, so for simplicity we wont store anything natively.

This also allows to have the entire config in one place for the "factory reset" functionality and loading defaults.

[MightyPork]

all done except the font-end