- simplify the code
- prevent to use "beta" tables from one decoder run to the next one (to see it
is the case, don't initialize beta, you will see it doesn't decode)
- decrease memory footprint of the decoder by x10 or more
- save about 15% of cpu in polartest unitary test tool, and more if we run in
realistic use case
- still this decoder performs much worse than the (very) slow OAI version by 3dB