start from 4.20 for automatic builds 

fixed 4.18 

fixed 4.21 build 

Update README.md 

ported to 4.15 

fixed autodetection for PyFbxFactory 20tab#488 

Merge pull request 20tab#504 from heylenz/master pyactor add function "set_actor_hidden_in_game"

added set_brutal_finalize() 

fixed 4.18 

Update MemoryManagement.md