Glamo Mesa Driver

Having realised that most of the bugs I was chasing aren't actually my fault (see the to-do list), I've been allowing myself to work on the Mesa driver for Glamo.  A rebase (sorry!) against the latest Git master branch of upstream Mesa was required to get some important DRI2 fixes, but now it works.  I'm not going to go into much detail (I need to sleep), but enough of the initialisation and buffering stuff works that things can be drawn (using Glamo's 2D engine at the moment) and then put on the screen (front buffer) successfully.  It's enough to draw a blue rectangle at the moment.  Not much, but you wouldn't believe how much Stuff has to be working correctly for that to happen.

Actually, I expect that readers of the journal would believe exactly how much Stuff is involved...