Implement SSID suffix stringes in pton()/ntop() to make it more
straightforward to specify addresses to bind, connect to, or add routes
for
Changes:
* Implement SSID suffix string formatting in patty_ax25_ntop(); drop
the 'ssid' pointer argument
* Implement SSID suffix string parsing in patty_ax25_pton(); drop
the 'ssid' argument
* Change all calls to patty_ax25_ntop() and patty_ax25_pton() to use
their new calling convention
Significantly simplify dictionaries so that dictionary keys are always
uint32_t; this number can be an arbitrary integer, be it a file
descriptor, for instance, or a hashed value
