Proper TDMA with both timeslots received

[kantooon]

You'll probably be pleased to know that I now have a branch which works with both timeslots and full TDMA BS access is implemented in https://github.com/qradiolink/qradiolink/tree/mmdvm_tdma

Tested using a LimeSDR-mini. Any LimeSDR device should work, and I think it can be adapted with minimum difficulties to work with USRPs, BladeRFs, or other devices which support RX and TX FPGA timestamps. I'll have a write-up soon on my website and I'll prepare the code for a new pull request.