added support for bhkRagdollTemplate (.rdt files)

Added support for bhkRagdollTemplate block based on two .rdt files (.rdt file is a .nif file) located in Fallout3 directory "meshes/ragdollconstraint". It seems that game uses only file "Default.rdt". Second file "stiff.rdt" is unused and suspicious because in NiHeader it has User Version 2 set to 16 instead of 34 as all Fallout3 files (and also Default.rdt) have.
Can anybody check Fallout New Vegas files if there are present any .rdt files? It would be good to have more than 2 files for decoding. Or exists other games with these files?
Merge pull request #22 from ttl269/feature/bhkRagdollTemplate-support

bhkRagdollTemplate support