It's not enabled by default because it doesn't fully work. It can
connect to an AP, get an IP address and do a host-lookup, but not yet do
send or recv on a socket.
All board config macros now begin with MICROPY_HW_.
Renamed PYBv10 to PYBV10, since macros should be all uppercase.
Made SDCARD_DETECT configurable in mpconfigport.h, so that the SD
detect pin can be easily configured.