Change date in license header to 2006-2010. This involves updating quite a few files, sorry.

Change date in license header to 2006-2010. This involves updating quite a few files, sorry.

git-svn-id: https://assimp.svn.sourceforge.net/svnroot/assimp/trunk@661 67173fc5-114c-0410-ac8e-9d2fd5bffc1f