Add code generator for convolutional codes

Add python utility to generate .c code with convolutional
encoder/decoder based on polynomial description of the code. If argument
given it'll be interpreted as intended output directory, otherwise
current working directory is used.

Codes for *CCH, CS2/3 and TCH/AFS are generated. Corresponding manual
implementations are removed from tests. This introduce build-time
dependency on python.

The main work for this patch was generously contributed by Sylvain
Munaut.

Fixes: OS#1629
7 files changed