Copy hydrocarbon files to hydrocarbon module in GhostFragment

[jlheflin]

Here is a starting point for the hydrocarbon module we talked about. I've been staring at this for a while and there's a good deal of mistakes. It currently does not compile.

Here is what I did:

• Reconstructed "hydrocarbon.cpp" from testing to include MODULE_DELCARE and MODULE_RUN, placing the majority of the hydrocarbon generating function under MODULE_RUN
• Added hydrocarbon.hpp to ghostfragment.hpp

[ryanmrichard]

I'm on my laptop and can't compile without closing everything else, but my changes should get this a lot closer to being merge-able. We still need a unit test for the module.

[jlheflin]

@ryanmrichard I had to make a few edits but it does work, I was able to generate a 200 carbon chain and there doesn't seem to be any inconsistencies with how the carbons and hydrogens are placed.

[ryanmrichard]

The hydrocarbon function is more tightly-coupled to the test environment of GhostFragment than I realized. This makes it hard to modularize without significant refactoring. For now I think the easiest solution is to just copy/paste the hydrocarbon function to ChemCache. I did that in NWChemEx/ChemCache#82.