Additional bonds

[SGrosse-Holz]

When plotting data with bonds shorter than 1 (absolute units), additional bonds are added in. (reported by Johannes, reproduced by me)

[SGrosse-Holz]

This is nglview... probably makes sense when visualizing actual molecules. Managed to reduce the issue a little bit by changing elements to helium (inert, small) and assigning (more or less) unique residue names, but it still happens for monomers that come close.

Added a scale option to xyz2nglview. If there are unwanted bonds, scale up by an appropriate factor.