Currently, when the coordIndex attribute of an IndexedLineSet contains a
polyline with > 2 indices, X3DGeoHelper::coordIdx_str2faces_arr() will
incorrectly determine the primitive type to be aiPrimitiveType_TRIANGLE or
aiPrimitiveType_POLYGON instead of aiPrimitiveType_LINE.
To fix this, this commit adds functions to explicitly handle an IndexedLineSet.
Fixes#3101
Andre Schulz
René Martin
kimkulling
Kim Kulling