extensions are *not* currently enabled.  This is for several reaons.  First,
the server-side does not support texture compression, so there's no
advantage to supporting it (yet) on the client-side.  Second, I tried
testing it with an IHV's closed-source driver (that advertises GL 1.3), but
their server-side driver doesn't support the protocol.  That means this code
is largely untested.