reworked the alt-az plates

Whoa. Figured it out. Finally, I found a way to effectively mount the bottom altitude-azimuth plates for the barn door tracker. It's only taken me 9 months!

In a moment of inspiration, I realised by turning the whole assembly upside-down, I could get the azimuth pivot point away from the hinges, and the azimuth adjuster would be away from the plate above.

A fringe benefit is there is now greater clearance for the altitude adjuster.