Add a section or page for medium-use tools

[RainierBarrett]

In wiki/Installing_the_Frequently-Used_Programs_for_CME-Lab.md, we have a guide on our most-frequently used software. There are other tools that tend to be useful, but used less frequently. Let's we make a section with links and info for these. For starters, Avogadro is pretty handy. If there are others you think should be included, please comment below.

[jennyfothergill]

OVITO https://www.ovito.org/