Combine notbit and notbit-sendmail into one executable

These two programs are now a single executable. The code for the
daemon has been moved from main.c to ntb-daemon.c and main.c now just
contains a short main function to determine which function to perform
based on argv[0]. A symbolic link is created for ntb-sendmail.
ipc-proto: Add helper functions to build an IPC message

Similar to the begin/end functions in ntb_proto, this adds functions
to build IPC commands.
Extract the client IPC code from ntb-sendmail into helper functions

The functions for sending a command and reading the response are now
moved to the ntb_ipc_* namespace so that they can also be used by
other utilities.
ipc: Use the ntb_ipc_proto_begin/end_command functions

The send_response function is now just a thin wrapper around the
shared utility functions in ntb_ipc_proto. Even the wrapper function
has been split up into begin and end commands so that it can be used
to build up a message in parts.
ipc: Add a keygen command

This adds a command to generate a new private key and return its
address in the response.
Add a utility to generate a new key

This issues the ‘keygen’ IPC request and prints the address it
generates to stdout.
keyring: Fix missing initialisers for some of the message cookie types
Add check unit test
Add first test
Change unit test framework to googletest

Testing C code with C++ testing frameworks seems quit common.
Add script for running testcases. Modified README
Tests for ntb-buffer
Propagate errors in the run_tests script
Clean blindfold git commit
Add test for base58
Fix encoding and decoding of zero in base58
Teach autoconf to cross compile
Ugly commit. just synchronziation to jakob
Ugly commit. just synchronziation to jakob
Ugly commit. just synchronziation to jakob