FINAL POLISHING (mostly just making the API more useable)

I genuinely can’t believe this. I did it, I made a renderer in Vulkan. Well, I’m still not in the clear yet, but I’m very close.

Changelog:

• updated Skin struct to include find_joint() function
• added Pose struct
• updated existing skinned mesh systems to work with the Pose struct
• added sample_clip(), compute_global_pose(), compute_skinning_matrices(), pose_set_local(), pose_set_global(), pose_get_global(), update_animation() and finalize_pose(). These are all helpers for making work with animated and rigged meshes a whole lot easier
• moved all of the functions inside the gvk namespace, because they were about half and half before.