The UI is optional and need to be explicitly activated, since I
don't want existing users to suddenly have an information-spewing
thing show up on their network.
Also introduces a "Trace" member to the API, for the future addition of
extremely verbose and complete tracing, to be used for bug reports. But
for now, only Log is used.
This version is still *extremely* barebones, and the unstable tag
in the README applies triple for it, but the code in its current
state is capable of booting x86 and UEFI clients correctly, and
that was hard enough to merit a snapshot checkpoint.
