Docs

[BTV25]

Basic documentation for FLOWVPM. Does not include the full API, just the most relevant parts.

[rymanderson]

Not quite ready yet.

[BTV25]

Looks like tests won't pass because the main branch is not up to date with the FastMultipole changes. I think it would be easiest if we upgraded the master branch and then fetched the changes into the docs branch.

[rymanderson]

@BTV25 Looking good! I think we still need:

• review how to incorporate different time stepping schemes, viscous models, SFS models, influence kernels, etc. under a Guided Examples tab
• the theory still reference ExaFMM under "Other Schemes" (should reference FastMultipole)