quaternioninterpolation

/** --
 ** Copyright (C) 2019 by Josh van den Heever
 **
 ** Permission is hereby granted, free of charge, to any person obtaining a copy of 
 ** this software and associated documentation files (the "Software"), to deal in 
 ** the Software without restriction, including without limitation the rights to 
 ** use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies 
 ** of the Software, and to permit persons to whom the Software is furnished to 
 ** do so, subject to the following conditions:
 **