pass japi_client context instead of raw socket ids

[fraunhofer-iis-bot]

In GitLab by @cstender on Jul 8, 2019, 15:57

It shall be discussed if we better pass a japi_client context instead of raw socket ids to the following functions:

• japi_remove_client
• japi_pushsrv_remove_client
• japi_process_message
• japi_pushsrv_subscribe
• japi_pushsrv_unsubscribe

[vornkat-iis]

Remove socket from japi_pushsrv_subscribe / japi_pushsrv_unsubscribe in 3eb513f to fit signature of a common request. Socket is instead passed through jreq.