Fix RSM

[kokosha]

Fix some calculation in RSM rendering

[vE5li]

Very nice! The game looks much better already :)

I made some small adjustments to your PR, notably:

• Remove temp_matrix and use transform_matrix instead, since it was always an identity matrix in the beginning
• Moved the version check to the load method so that we can load a fallback model in case of an unsupported version
• (Minor) Use for_each for calculate_transformation_matrix on the child nodes