[Xcb] "Plan 7" documented, 32-bit wrap in progress

[Barton C Massey]

Ian, Keithp and I refactored the XCB API documentation a bit
tonight, documented the tiny "Xlib" XCB API, and added
documentation on the upcoming "Plan 7" XCB error handling.
Hopefully Josh will now help us with the XSLT needed to
implement Plan 7.

In other news of the evening, Keithp is basically done
getting 32-bit sequence number wrap to work properly in XCB
and Xlib/XCB.  XCB is committed, Xlib/XCB should be
committed shortly.

Getting pretty close to a general Xlib/XCB release.

    Bart