drone climbing stuff

[jhh8]

• bottom climb node has to be half way inside the ground for the climbing to work, which is very not intuitive for mappers
• first drone to climb up falls down, rest climb fine
• would be cool if drones could climb downwards or at an angle. currently they can climb downwards but have the climb upwards animation, climbing at an angle doesnt work

[BenLubar]

If we had more animations for turning (or better yet, some kind of pose parameter based blended turning animation) it would be very cool to let climbing nodes go in absolutely any direction, but the code right now is based on fast zombies from Half-Life 2, so it'll need some tweaking or possibly a rewrite.