Added support for the 0C45:7402 TEMPerHumM12V1.2, which uses a Si7021 sensor.

[forrestv]

Verified to match another hygrometer to within 1% RH and 3 °C.

Here are some pictures if you're interested: http://u.forre.st/TEMPerHumM12V1.2/

[davet2001]

Yes, this works for me. Actually I had to make a further minor enhancement to support TEMPerHumM12V1.3 which is what my device is. I don't seem to be able to submit this mod though. Sorry I don't know how to use git. In SVN speak I am trying to commit a change to the TEMPerHum12V1.2 branch. Maybe I can't because it's not been merged yet. I have some files and they work.

I have tried to attach the patch. Sorry I don't know what I'm doing.

TEMPerHUM12V1.3.patch.txt

[normanr]

@davet2001 I created a pull request for your branch: #40