[Xcb] XcbApi wiki page now up

[Jeremy Kolb]

I just imported the XcbApi wiki page and cleaned it up a lot.  It's 
still horribly busted though (All #links are broken, some formatting 
issues).  Can someone take a look and clean it up the rest of the way as 
I'm not really sure how this works.  Also someone needs to verify that 
this is up to date and correct.  I believe this is the last of the old 
pages to be moved over (really I hope it is, not entirely sure).

Jeremy