string_to_pdp_type is only used in CellularContext classes and by having
the conversion method in CellularContext it can be used to check also
the non-standard Non-IP PDP type string.
CellularContext member variables were initialized in inheriting class.
Now in base class where they should be initialized so that every inheriting
class don't have to init them.
Disconnect was sent to all CellularContext classes even it concerned
one specific context. Some disconnect events are still sent to all
context classes. These event are coming from network and ment for all
context classes or event did not specify cid.
State machine has retry logic until device is attached to network.
After this CellularContext does the context activation e.g. connect.
There was no retry logic for context activation. Added logic to
CellularContext level so it's available for at and (upcoming)ril layers.
When using NetworkInterface::get_default_instance() application gets handle
to CellularInterface which is actually CellularContext derived from CellularInterface.
Application needs also handle to CellularDevice to open other interfaces.
Kimmo Vaisanen
Teppo Järvelin