Ability to specify RConnection instance etc in PJLIB Symbian

[bennylp]

Some applications want to be able to specify RConnection instance to be used by PJLIB.

[bennylp]

Done in r1525:

1. Added pj_symbianos_set_params() function in os.h. This function MUST be called before calling pj_init().
2. Application can (optionally) specify these objects in pj_symbianos_set_params():
   • RSocketServ instance,
   • RConnection instance, and
   • RHostResolver instance.
3. When RSocketServ instance is specified, this instance will be used for all socket related objects in PJLIB. Otherwise PJLIB will create a new RSocketServ instance in pj_init().
4. When RConnection instance is specified, this instance will be used when creating the internal RHostResolver, and all sockets. The exception of this is when PJLIB creating a blank socket for accept(), where only RSocketServ instance is specified. If RConnection is not specified, then all related operations will not utilize RConnection instance.
5. When RHostResolver instance is specified, this instance will be used in PJLIB, otherwise a new instance will be created using RSocketServ and RConnection instances above if they are specified.