fix(tools): allow conversion of .fbx files regardless of case
fix(tools): allow conversion of .fbx files regardless of case

When I bulk exported Paragon animations using the Unreal Editor, it
named the files .FBX, which were not accepted by fbx2acl.py.

nfrechette/acl,nfrechette/acl,nfrechette/acl,nfrechette/acl,nfrechette/acl