Add EcoWitt WH31B support by modifying WH31E

[bitfliq]

Added samples here: merbanan/rtl_433_tests#394 , https://github.com/bitfliq/rtl_433_tests/tree/EcoWitt-WH31B .

This code worked for extracting data from WH31B - but I was unable to verify that it did not break the other devices.

Thanks for all of your hard work on this fantastic project.

[bitfliq]

Closing due to instability. Will reopen after fixes in place.

[zuckschwerdt]

Notes:

• leave the crc-error distinction out, maybe add (%d) ... msg_type
• leave long/short id out, use:
• "model", "", DATA_COND, msg_type == 0x30, DATA_STRING, "AmbientWeather-WH31E",
"model", "", DATA_COND, msg_type == 0x37, DATA_STRING, "AmbientWeather-WH31B",

[bitfliq]

Thanks @zuckschwerdt for friendly feedback. Instability seems resolved with your suggestions. Not confident I matched what you were looking for with crc-error distinction recommendation.

[zuckschwerdt]

Looks mostly good, thanks! I meant to say: just change the error strings, e.g. "WH31E bad CRC" to "WH31E/WH31B bad CRC", there is no real need to have a switch on the msg_type there (just %d, like you did) -- shorter code is more legible :)

Perhaps we should keep CRC/SUM separate, so e.g. fprintf(stderr, "%s: WH31E/WH31B (%s) bad CRC\n", __func__, msg_type);

[bitfliq]

@zuckschwerdt Could you please take another look?