The send and receive window is now managed by an external object.
There are some issues that can only be solved with C++11 but it
is progres and removes some of the spaghetti code. For GPRS the
sns and ws is hardcoded. Move that into the window code.
Whenwe receive a final ack we assume that all the unacked frames
have been acked now. Move the counting to V_B and now the caller
can remove the BSN and the "lost" variable which has always been
zero.
Move the parsing of the bitbmap out of the TBF code into Decoding.
Move the updating of the V_B into the V_B class. Add some comments
about handling the mod_sns, mod_sns_half parameters by using template
code.