Montague's Mount: Shadow fix thanks to 4everAwake

"And adjust c220.y until the shadows are aligned with the ground. A higher
number makes the shadows go down. This should fix directional (ambient) light
shadows. Spot lights & shadows may also need adjustment, though."

I found 1.13 seems to be about right for the shadows in this game.
Montague's Mount: Use Harry Potter profile by default - more stable than Aion

Thanks for the tip 4everAwake - I still get flickering, but it doesn't seem to
be anywhere near as often as the Aion profile.
Montague's Mount: Add title screen background shader
Montague's Mount: Adjust title screen background depth
Montague's Mount: Fix lens flare

Turns out the lens flare is not only broken, but also uses the same vertex
shader as part of the UI, so we need to do two different fixes in the one
shader depending on what is being drawn.

If the lens flare texture is matched, undo the stereo correction formula, than
adjust it to a fixed depth. This is an approximation, but it looks pretty good
to me.
Montague's Mount: Update README.md