Convert numpy in32 to int for `getElement` call

ccLib returns the molecule attributes, such as atom numbers
and atom coordinates, using numpy objects. The `getElement`
method needs an int.
Move `setImages` to `GaussianTS` from `GaussianTSB3LYP`

This is a more general method than was previously set.

Also changed from the ASE image creator to building an ASE atom
image manually. There were some errors being returned from ASE
about the number of atoms and coordinates being different.