benchmark: add tcp swich and make more netperf-like

1: For a more accurate comparison between TCP and TIPC performance, we
   add a switch to client_tipc that makes it possible to choose which
   type of connection we want to measure. IP port number and address
   are transported transparently (via TIPC) from server to client, so
   it is equally easy to use the benchmark with TCP as with TIPC. The
   tests and the measurements are exactly the same for both protocols.

2: The whole framework is reworked, so that "master" now has strict
   control over both client and server, e.g., telling them how many and
   what size of messages to expect in each iteration. As a result, it
   is now possible to use MSG_WAITALL when reading messages at the
   server side.

3: Calcualtions of results are now made more accurate, and presented
   with more decimals in a comprehensible table format.

4: The thoughput test is now based on a one-way stream from client
   to server, to make the results more comparable with what one gets
   from netperf.

Somebody should add an AF_UNIX/SOCK_STREAM option too. It should be
easy given the new framework.