V.110 defines a B-channel protocol for transmission of synchronous and
asynchronous serial data of V-series interfaces via terminal adapters
over ISDN.
Let's add (unoptimized but easy to debug) functions for encoding and
decoding of V.110 frames for various bit-rates.
Related: OS#1572
Change-Id: I1b5fd3847d3bfb0a0f763e0574893962ec699680