Improved third person experience

More realistic strafe movement and a new mode of third person view.

Resolves #390 (closed) and #5457 (closed).

Discussed in the topic: https://forum.openmw.org/viewtopic.php?f=24&t=6955

New features

Third person camera behaviour

• In non-combat mode camera is positioned above the right shoulder to make the activation direction better visible.
• In combat mode camera is positioned above the character's head because otherwise it would affect aiming.
• Aim cross is visible even in third person mode.
• When player looks down, the camera goes a bit farther away from the character. After some testing I found it very convenient.

Non-combat movement

• Head is pointed to the direction of view.
• Lower body is rotated to the direction of movement.
• Upper body is only partially rotated.
• Strafe animation is not used at all.

Combat movement

• Strafe animation is used only for straight left and straight right movement.
• Head is pointed to the direction of view.
• Lower body is rotated to the direction of movement.
• Upper body is rotated only a bit. All attacks are still pointed forward.

How to enable

By default the new features are disabled. Can be enabled in settings.cfg with:

[Camera]
view over shoulder = true

[Game]
turn to movement direction = true

Testing

I've manually checked that:

• Game doesn't crash;
• There is no visible changes if the new features are not enabled in settings;
• The new features, in my impression, improve game experience;
• Movement looks reasonable for all directions in all modes: walking, running, sneaking, swimming.

Not tested:

• New way of diagonal movement should work for all NPCs as well, not only for player. But NPCs usually do not use strafing, so to properly test it we may need a special AI package.