Interpolate between <code>this</code> {@link #normalize() unit} quaternion and the specified
<code>target</code> {@link #normalize() unit} quaternion using spherical linear interpolation using the specified interpolation factor <code>alpha</code>.
<p>
This method resorts to non-spherical linear interpolation when the absolute dot product between <code>this</code> and <code>target</code> is
below <code>1E-6</code>.
@param target
the target of the interpolation, which should be reached with <code>alpha = 1.0</code>
@param alpha
the interpolation factor, within <code>[0..1]</code>
@return this
Interpolate between <code>this</code> {@link #normalize() unit} quaternion and the specified <code>target</code> {@link #normalize() unit} quaternion using spherical linear interpolation using the specified interpolation factor <code>alpha</code>. <p> This method resorts to non-spherical linear interpolation when the absolute dot product between <code>this</code> and <code>target</code> is below <code>1E-6</code>.
@param target the target of the interpolation, which should be reached with <code>alpha = 1.0</code> @param alpha the interpolation factor, within <code>[0..1]</code> @return this