Various improvements (2D navigation, PhysicsRayCast, examples upgrades, important bug

[DP News-Robot]

The navigation in 2D viewports (with orthographic projection and standard direction/up: -Z/+Y) is now much better. We have a new algorithm TCastleExamineNavigation.ExactMovement that makes the navigation more natural, and we have a dedicated TCastle2DNavigation class (descendant of TCastleExamineNavigation) to make the mouse buttons easiest to discover (just drag with left mouse button). You can assign …