- Added support for separate normal map filename tag in XFile material list
- shortened texture type determination in XFile loader while I was there
- Bugfix: ValidateDataStructure wrongly flagged animations with zero duration as error
git-svn-id: https://assimp.svn.sourceforge.net/svnroot/assimp/trunk@76 67173fc5-114c-0410-ac8e-9d2fd5bffc1f