mmisc::mtime::Timer now has create() which returns a reference to a new
object -- which a reference can be initialized to. I'm doing this so
that mui::Interface::timer doesn't have to be a pointer or const
reference, but can be a plain old reference initialized in the ctor
initialization list without callers having to worry about allocating the
timer -- the ctor will handle that via Interface() :
timer(mmisc::mtime::Timer::create()).