Fix an issue where camera position isn't used in grid calculation

[disusdev]

The camera position was missed from the grid calculation, so the grid always stuck in the origin.

[corporateshark]

1. What does it change visually?

2. This changeset breaks Chapter 7.

[disusdev]

Oh, I see, my fault, I forgot about an infinite plane. Here is the fix for that.
So the grid stays always in world origin, as we render the plane, but it is called an infinite grid, so I've added camera XZ position to plane and UV, to make sure that it will always draw the grid on camera XZ position.

Before:

After:

[corporateshark]

Thank you for your contribution!