Implement socket options for tcp keepalive and close timeout

The following additional socket option shall be implemented for internal usage and packet socket api:

• SO_KEEPALIVE: This option is used to enable keep alive for the socket. (Will be implemented for TCP only). It shall be used in conjuction with layer SOL_SOCKET.
• TCP_KEEPINTVL: This option can be used to set the TCP keepalive interval in seconds. It shall be used in conjuction with layer IPPROTO_TCP
• TCP_KEEPIDLE: This option can be used to set the TCP keepalive idle in seconds. This is the time after the last real TCP transaction the first keep alive probe will be sent. It shall be used in conjuction with layer IPPROTO_TCP.
• TCP_KEEPCNT: This is the maximum number of keep alive probes to be sent before the connection shall be dropped. It shall be used in conjuction with layer IPPROTO_TCP
• SO_LINGER: This is the number of seconds the socket will stay in TIME-WAIT state after closing by application. Default value is 120s. (2x TCP MSL) As long as in TIME-WAIT, the socket can not be reused. It shall be used in conjuction with layer SOL_SOCKET