vaporgui core dumps during key frame animation on linux
To reproduce:
1. Load the attached session file and the KatrinaVDC2/Katrinavdc2.vdf data set
2. Enable image and iso
3. enable key framing
4. Animate. vaporgui will core dump before the animation completes
The problem was that the number of frames between keyframes was sometimes not being updated when a new interpolation was calculated.