Bugfix: if a SYN is received in the SYN_RCVD state we should not send a blank SYN, but a SYNACK in response.
Bugfix: correctly handle the case if uip_sappdata is NULL.
Allow the default TTL to be configured with UIP_CONF_TTL
Produce an error if the UIP_TCP_MSS is too large for UIP_BUFSIZE
Travis test for slip-radio
Merge pull request #457 from adamdunkels/push/uip6-bugfixes

IPv6 bugfixes
Merge pull request #155 from cetic/travis-slip-radio

Travis test for slip-radio