Release 1.9 changes

As we discussed, there is no need to slide the window timing around, so this leaves just the RTSCTS fixes and a version number bump.  I've also made the changes which I _think_ will make the RFD antenna selection show up in the upper bit of the txbuf radio status, but I don't have a RFD900 to test with.

I recommend you merge https://github.com/geeksville/SiK/tree/rfd-ant-bit-wip into this before releasing and testing that the antenna selection appears.  The only commit needed for that change is: https://github.com/geeksville/SiK/commit/1d0f608fbe80f2dca3d80fb8dd5a1704703ec860