Allow Sip Call-ID to be set instead of generated by library.

[austinkottke]

We need to be able to set the call-id of an outgoing invite.

On each release of pjsip I manually patch the libary.

Please consider writing or including a new structure: pjsip_dialog_options

pjsip_dlg_create_uac2(
                const pjsip_dlg_create_uac_param *create_param,
                pjsip_dialog **p_dlg, const pjsip_dialog_options *options)
               {

               if( options->sipCallId != NULL ){
                 pj_strcpy(&dlg->call_id->id, options->sipCallId->ptr);
             }
} 

Thank you.

[sauwming]

Not planned.