keepalive server cs357x and cs378x

It will disable the general oscam clienttimeout on the related server protocol (oscam.conf section [cs357x] or [378x]) if keepalive = 1 or checked in webif.  For cs357x only prevents client kill. By cs387x prevents client and resulting tcp_disconnection. Default 0.

git-svn-id: http://streamboard.de.vu/svn/oscam/trunk@9798 4b0bc96b-bc66-0410-9d44-ebda105a78c1