removed trailing spaces and tabs from source and text

This commit ignores the “contrib” folder in order to prevent merge conflicts in dependencies, should these be updated via git.

test/unit/SceneDiffer.cpp

@@ -48,7 +48,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 namespace Assimp {
 
-SceneDiffer::SceneDiffer() 
+SceneDiffer::SceneDiffer()
 : m_diffs() {
     // empty
 }