- eth0 => ethX in several examples
 - added @todo in Dhcp6Srv, getMAC() is now static
 - added @todo in CfgMACSource

 - Moved MAC operations to a new CfgMACSource class
 - Moved macros to HWaddr class
 - Added several unit-tests for MAC sources
 - MAC extraction code moved to separate function in Dhcpv6Srv

 - clarified that order in mac-sources is important
 - tweaked all examples to use eth9 rather than more common eth0

One of the reservations is within the pool of dynamically allocated
addresses. The example demonstrates that the server will not allocate
this address dynamically and will only assign it to the client that
has a reservation for it.

Both Ubuntu and NetBSD builds fail because of what appears to be an error
trying to the use "equal_range" method of one of the classes associated with
the Boost multi-index container. The cause is uncertain - other systems
build successfully, so the problem might no lie here, e.g. it could be in
the compiler.  This fix attempts to side-step the problem by modifying the
affected files so as not to use this method.

The new tests are implemented using the Dhcp4Client class. It has been
found that the server returns DHCPNAK in response to DHCPDISCOVER which
was wrong. Now, the server doesn't respond to DHCPDISCOVER if it can't
find an address. As a result, a number of tests had to be fixed which
relied on this invalid behavior.