Zoom out a bit in 3D dialog

[arouinfar]

Discovered in #148

If a molecule is very large, it may not fit inside the viewing window of the 3D dialog, regardless of the representation (space filling or ball-and-stick). For example:

@Denz1994 can you zoom the view out a bit? This would be a universal adjustment, not just for large molecules.

[Denz1994]

Can you check out the zoom distance on master @arouinfar? The camera should be zoomed out to capture more of the molecule.

[arouinfar]

The zoom level in master is looking good. Thanks @Denz1994.